diff --git a/.opt-prof.yml b/.opt-prof.yml
index ee9d1649fee..38796eed3b8 100644
--- a/.opt-prof.yml
+++ b/.opt-prof.yml
@@ -57,7 +57,6 @@ stages:
     cloudBuildResourceName: ComponentBuildUnderTest
     testLabPoolName: VS-Platform # The test lab pool to run your tests in
     testMachineCleanUpStrategy: ${{parameters.testMachineCleanUpStrategy}}
-    testMachineImageName: Windows-11-Enterprise-23H2
     visualStudioSigning: Test
     variables:
     - name: branchName # The branch in the VS repo the bootstrapper was based on
diff --git a/documentation/wiki/ChangeWaves.md b/documentation/wiki/ChangeWaves.md
index 304e6b3a8b3..6b88ed66097 100644
--- a/documentation/wiki/ChangeWaves.md
+++ b/documentation/wiki/ChangeWaves.md
@@ -25,7 +25,7 @@ A wave of features is set to "rotate out" (i.e. become standard functionality) t
 ## Current Rotation of Change Waves
 
 ### 17.14
-- [.SLNX support - use the new parser for .sln and .slnx](https://github.com/dotnet/msbuild/pull/10836)
+- ~[.SLNX support - use the new parser for .sln and .slnx](https://github.com/dotnet/msbuild/pull/10836)~ reverted after compat problems discovered
 - [Support custom culture in RAR](https://github.com/dotnet/msbuild/pull/11000)
 - [VS Telemetry](https://github.com/dotnet/msbuild/pull/11255)
 
diff --git a/eng/BootStrapMsBuild.targets b/eng/BootStrapMsBuild.targets
index d4330ba658d..dcff8617638 100644
--- a/eng/BootStrapMsBuild.targets
+++ b/eng/BootStrapMsBuild.targets
@@ -35,8 +35,7 @@
         <_NuGetRuntimeDependencies Include="%(RuntimeCopyLocalItems.Identity)" Condition="'@(RuntimeCopyLocalItems->Contains('Newtonsoft.Json'))' == 'true'" />
         <_NuGetRuntimeDependencies Include="%(RuntimeCopyLocalItems.Identity)" Condition="'@(RuntimeCopyLocalItems->Contains('NuGetSdkResolver'))' == 'true'" />
         <_NuGetRuntimeDependencies Include="%(RuntimeCopyLocalItems.Identity)" Condition="'@(RuntimeCopyLocalItems->Contains('Microsoft.Extensions.'))' == 'true'" />
-        <_NuGetRuntimeDependencies Include="%(RuntimeCopyLocalItems.Identity)" Condition="'@(RuntimeCopyLocalItems->Contains('Microsoft.VisualStudio.SolutionPersistence'))' == 'true'" />
-      
+
         <!-- NuGet.targets and NuGet.RestoreEx.targets will be in the RuntimeTargetsCopyLocalItems ItemGroup -->
         <_NuGetRuntimeDependencies Include="%(RuntimeTargetsCopyLocalItems.Identity)" Condition="'@(RuntimeTargetsCopyLocalItems->Contains('NuGet.'))' == 'true'" />
 
@@ -49,7 +48,7 @@
 
   <Target Name="RemoveExtraAssemblyReferences" BeforeTargets="ResolveAssemblyReferences">
     <!-- This is really hacky, but these references will cause issues when trying to 'build' this project.
-         To acquire the NuGet binaries we depend on for local run-time ('bootstrap'), we are using a PackageReference (to
+         To acquire the NuGet binaries we depend on for local run-time ('bootstrap'), we we are using a PackageReference (to
          'NuGet.Build.Tasks' and 'Microsoft.Build.NuGetSdkResolver'). This has the advantage of using NuGets compatibility
          check to ensure we choose the right version of those assemblies. But, at 'bootstrap' time these runtime dependencies
          need to be in a specific location that does not mesh with NuGet. To resolve this, we include the default
diff --git a/src/Build.OM.UnitTests/Construction/SolutionFile_Tests.cs b/src/Build.OM.UnitTests/Construction/SolutionFile_Tests.cs
index fcf15461cc3..d6abd900521 100644
--- a/src/Build.OM.UnitTests/Construction/SolutionFile_Tests.cs
+++ b/src/Build.OM.UnitTests/Construction/SolutionFile_Tests.cs
@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -32,31 +31,31 @@ public class SolutionFile_Tests
         [Fact]
         public void ParseSolution_VC()
         {
-            string solutionFileContents =
-            """
-            Microsoft Visual Studio Solution File, Format Version 9.00
-            # Visual Studio 2005
-            Project('{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}') = 'Project name.vcproj', 'Relative path\to\Project name.vcproj', '{0ABED153-9451-483C-8140-9E8D7306B216}'
-            EndProject
-            Global
-                GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                    Debug|AnyCPU = Debug|AnyCPU
-                    Release|AnyCPU = Release|AnyCPU
-                EndGlobalSection
-                GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                    {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.ActiveCfg = Debug|AnyCPU
-                    {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.Build.0 = Debug|AnyCPU
-                    {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.ActiveCfg = Release|AnyCPU
-                    {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.Build.0 = Release|AnyCPU
-                EndGlobalSection
-                GlobalSection(SolutionProperties) = preSolution
-                    HideSolutionNode = FALSE
-                EndGlobalSection
-            EndGlobalf
-            """;
-
             Assert.Throws<InvalidProjectFileException>(() =>
             {
+                string solutionFileContents =
+                    @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}') = 'Project name.vcproj', 'Relative path\to\Project name.vcproj', '{0ABED153-9451-483C-8140-9E8D7306B216}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|AnyCPU = Debug|AnyCPU
+                        Release|AnyCPU = Release|AnyCPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.ActiveCfg = Debug|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.Build.0 = Debug|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.ActiveCfg = Release|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.Build.0 = Release|AnyCPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                EndGlobal
+                ";
+
                 ParseSolutionHelper(solutionFileContents);
                 Assert.Fail("Should not get here");
             });
@@ -97,7 +96,7 @@ public void ParseSolution_VC2(bool convertToSlnx)
 
             string expectedProjectName = convertToSlnx ? "Project name" : "Project name.myvctype";
             Assert.Equal(expectedProjectName, solution.ProjectsInOrder[0].ProjectName);
-            Assert.Equal(ConvertToUnixPathIfNeeded("Relative path\\to\\Project name.myvctype"), solution.ProjectsInOrder[0].RelativePath);
+            Assert.Equal(ConvertToUnixPathIfNeeded("Relative path\\to\\Project name.myvctype", convertToSlnx), solution.ProjectsInOrder[0].RelativePath);
             if (!convertToSlnx)
             {
                 // When converting to SLNX, the project GUID is not preserved.
@@ -105,6 +104,42 @@ public void ParseSolution_VC2(bool convertToSlnx)
             }
         }
 
+        /// <summary>
+        /// A slightly more complicated test where there is some different whitespace.
+        /// </summary>
+        [Fact]
+        public void ParseSolutionWithDifferentSpacing()
+        {
+            string solutionFileContents =
+                @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project(' { Project GUID} ')  = ' Project name ',  ' Relative path to project file '    , ' {0ABED153-9451-483C-8140-9E8D7306B216} '
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|AnyCPU = Debug|AnyCPU
+                        Release|AnyCPU = Release|AnyCPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.ActiveCfg = Debug|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.Build.0 = Debug|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.ActiveCfg = Release|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.Build.0 = Release|AnyCPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+            SolutionFile solution = ParseSolutionHelper(solutionFileContents);
+
+            Assert.Equal("Project name", solution.ProjectsInOrder[0].ProjectName);
+            Assert.Equal("Relative path to project file", solution.ProjectsInOrder[0].RelativePath);
+            Assert.Equal("{0ABED153-9451-483C-8140-9E8D7306B216}", solution.ProjectsInOrder[0].ProjectGuid);
+        }
+
         /// <summary>
         /// Solution with an empty project name.  This is somewhat malformed, but we should
         /// still behave reasonably instead of crashing.
@@ -113,33 +148,146 @@ public void ParseSolution_VC2(bool convertToSlnx)
         public void ParseSolution_EmptyProjectName()
         {
             string solutionFileContents =
-            """
-            Microsoft Visual Studio Solution File, Format Version 9.00
-            # Visual Studio 2005
-            Project('{Project GUID}') = '', 'src\.proj', '{0ABED153-9451-483C-8140-9E8D7306B216}'
-            EndProject
-            Global
-                GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                    Debug|AnyCPU = Debug|AnyCPU
-                    Release|AnyCPU = Release|AnyCPU
-                EndGlobalSection
-                GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                    {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.ActiveCfg = Debug|AnyCPU
-                    {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.Build.0 = Debug|AnyCPU
-                    {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.ActiveCfg = Release|AnyCPU
-                    {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.Build.0 = Release|AnyCPU
-                EndGlobalSection
-                GlobalSection(SolutionProperties) = preSolution
-                    HideSolutionNode = FALSE
-                EndGlobalSection
-            EndGlobal
-            """;
+                           @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{Project GUID}') = '', 'src\.proj', '{0ABED153-9451-483C-8140-9E8D7306B216}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|AnyCPU = Debug|AnyCPU
+                        Release|AnyCPU = Release|AnyCPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.ActiveCfg = Debug|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.Build.0 = Debug|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.ActiveCfg = Release|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.Build.0 = Release|AnyCPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+            SolutionFile solution = ParseSolutionHelper(solutionFileContents);
+
+            Assert.StartsWith("EmptyProjectName", solution.ProjectsInOrder[0].ProjectName);
+            Assert.Equal("src\\.proj", solution.ProjectsInOrder[0].RelativePath);
+            Assert.Equal("{0ABED153-9451-483C-8140-9E8D7306B216}", solution.ProjectsInOrder[0].ProjectGuid);
+        }
+
+        /// <summary>
+        /// Test some characters that are valid in a file name but that also could be
+        /// considered a delimiter by a parser. Does quoting work for special characters?
+        /// </summary>
+        [Fact]
+        public void ParseSolutionWhereProjectNameHasSpecialCharacters()
+        {
+            string solutionFileContents =
+                           @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{Project GUID}')  = 'MyProject,(=IsGreat)',  'Relative path to project file'    , '{0ABED153-9451-483C-8140-9E8D7306B216}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|AnyCPU = Debug|AnyCPU
+                        Release|AnyCPU = Release|AnyCPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.ActiveCfg = Debug|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.Build.0 = Debug|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.ActiveCfg = Release|AnyCPU
+                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.Build.0 = Release|AnyCPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+            SolutionFile solution = ParseSolutionHelper(solutionFileContents);
+
+            Assert.Equal("MyProject,(=IsGreat)", solution.ProjectsInOrder[0].ProjectName);
+            Assert.Equal("Relative path to project file", solution.ProjectsInOrder[0].RelativePath);
+            Assert.Equal("{0ABED153-9451-483C-8140-9E8D7306B216}", solution.ProjectsInOrder[0].ProjectGuid);
+        }
 
+        /// <summary>
+        /// Ensure that a bogus version stamp in the .SLN file results in an
+        /// InvalidProjectFileException.
+        /// </summary>
+        [Fact]
+        public void BadVersionStamp()
+        {
+            Assert.Throws<InvalidProjectFileException>(() =>
+            {
+                string solutionFileContents =
+                    @"
+                Microsoft Visual Studio Solution File, Format Version a.b
+                # Visual Studio 2005
+                ";
+
+                ParseSolutionHelper(solutionFileContents);
+            });
+        }
+        /// <summary>
+        /// Expected version numbers less than 7 to cause an invalid project file exception.
+        /// </summary>
+        [Fact]
+        public void VersionTooLow()
+        {
             Assert.Throws<InvalidProjectFileException>(() =>
             {
-                SolutionFile solution = ParseSolutionHelper(solutionFileContents);
+                string solutionFileContents =
+                    @"
+                Microsoft Visual Studio Solution File, Format Version 6.0
+                # Visual Studio 2005
+                ";
+
+                ParseSolutionHelper(solutionFileContents);
             });
         }
+        /// <summary>
+        /// Test to parse a very basic .sln file to validate that description property in a solution file
+        /// is properly handled.
+        /// </summary>
+        [Fact]
+        public void ParseSolutionFileWithDescriptionInformation()
+        {
+            string solutionFileContents =
+                @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'AnyProject', 'AnyProject\AnyProject.csproj', '{2CAB0FBD-15D8-458B-8E63-1B5B840E9798}'
+                EndProject
+                Global
+	                GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		                Debug|Any CPU = Debug|Any CPU
+		                Release|Any CPU = Release|Any CPU
+		                Description = Some description of this solution
+	                EndGlobalSection
+	                GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		                {2CAB0FBD-15D8-458B-8E63-1B5B840E9798}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		                {2CAB0FBD-15D8-458B-8E63-1B5B840E9798}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		                {2CAB0FBD-15D8-458B-8E63-1B5B840E9798}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		                {2CAB0FBD-15D8-458B-8E63-1B5B840E9798}.Release|Any CPU.Build.0 = Release|Any CPU
+	                EndGlobalSection
+	                GlobalSection(SolutionProperties) = preSolution
+		                HideSolutionNode = FALSE
+	                EndGlobalSection
+                EndGlobal
+                ";
+            try
+            {
+                ParseSolutionHelper(solutionFileContents);
+            }
+            catch (Exception ex)
+            {
+                Assert.Fail("Failed to parse solution containing description information. Error: " + ex.Message);
+            }
+        }
 
         /// <summary>
         /// Tests the parsing of a very basic .SLN file with three independent projects.
@@ -190,17 +338,17 @@ public void BasicSolution(bool convertToSlnx)
 
             // When converting to slnx, the order of the projects is not preserved.
             ProjectInSolution consoleApplication1 = solution.ProjectsInOrder.First(p => p.ProjectName == "ConsoleApplication1");
-            Assert.Equal(ConvertToUnixPathIfNeeded("ConsoleApplication1\\ConsoleApplication1.vbproj"), consoleApplication1.RelativePath);
+            Assert.Equal(ConvertToUnixPathIfNeeded("ConsoleApplication1\\ConsoleApplication1.vbproj", convertToSlnx), consoleApplication1.RelativePath);
             Assert.Empty(consoleApplication1.Dependencies);
             Assert.Null(consoleApplication1.ParentProjectGuid);
 
             ProjectInSolution vbClassLibrary = solution.ProjectsInOrder.First(p => p.ProjectName == "vbClassLibrary");
-            Assert.Equal(ConvertToUnixPathIfNeeded("vbClassLibrary\\vbClassLibrary.vbproj"), vbClassLibrary.RelativePath);
+            Assert.Equal(ConvertToUnixPathIfNeeded("vbClassLibrary\\vbClassLibrary.vbproj", convertToSlnx), vbClassLibrary.RelativePath);
             Assert.Empty(vbClassLibrary.Dependencies);
             Assert.Null(vbClassLibrary.ParentProjectGuid);
 
             ProjectInSolution classLibrary1 = solution.ProjectsInOrder.First(p => p.ProjectName == "ClassLibrary1");
-            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary1\\ClassLibrary1.csproj"), classLibrary1.RelativePath);
+            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary1\\ClassLibrary1.csproj", convertToSlnx), classLibrary1.RelativePath);
             Assert.Empty(classLibrary1.Dependencies);
             Assert.Null(classLibrary1.ParentProjectGuid);
 
@@ -217,10 +365,88 @@ public void BasicSolution(bool convertToSlnx)
         /// solution folders will get correctly uniquified.
         /// For the new parser, solution folders are not included to ProjectsInOrder or ProjectsByGuid.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void SolutionFolders(bool convertToSlnx)
+        [Fact]
+        public void SolutionFolders()
+        {
+            string solutionFileContents =
+                @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{34E0D07D-CF8F-459D-9449-C4188D8C5564}'
+                EndProject
+                Project('{2150E333-8FDC-42A3-9474-1A3956D46DE8}') = 'MySlnFolder', 'MySlnFolder', '{E0F97730-25D2-418A-A7BD-02CAFDC6E470}'
+                EndProject
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'MyPhysicalFolder\ClassLibrary1\ClassLibrary1.csproj', '{A5EE8128-B08E-4533-86C5-E46714981680}'
+                EndProject
+                Project('{2150E333-8FDC-42A3-9474-1A3956D46DE8}') = 'MySubSlnFolder', 'MySubSlnFolder', '{2AE8D6C4-FB43-430C-8AEB-15E5EEDAAE4B}'
+                EndProject
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary2', 'ClassLibrary2\ClassLibrary2.csproj', '{6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|Any CPU = Debug|Any CPU
+                        Release|Any CPU = Release|Any CPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {34E0D07D-CF8F-459D-9449-C4188D8C5564}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {34E0D07D-CF8F-459D-9449-C4188D8C5564}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                        {34E0D07D-CF8F-459D-9449-C4188D8C5564}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                        {34E0D07D-CF8F-459D-9449-C4188D8C5564}.Release|Any CPU.Build.0 = Release|Any CPU
+                        {A5EE8128-B08E-4533-86C5-E46714981680}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {A5EE8128-B08E-4533-86C5-E46714981680}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                        {A5EE8128-B08E-4533-86C5-E46714981680}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                        {A5EE8128-B08E-4533-86C5-E46714981680}.Release|Any CPU.Build.0 = Release|Any CPU
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}.Release|Any CPU.Build.0 = Release|Any CPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                    GlobalSection(NestedProjects) = preSolution
+                        {A5EE8128-B08E-4533-86C5-E46714981680} = {E0F97730-25D2-418A-A7BD-02CAFDC6E470}
+                        {2AE8D6C4-FB43-430C-8AEB-15E5EEDAAE4B} = {E0F97730-25D2-418A-A7BD-02CAFDC6E470}
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4} = {2AE8D6C4-FB43-430C-8AEB-15E5EEDAAE4B}
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+            SolutionFile solution = ParseSolutionHelper(solutionFileContents);
+
+            Assert.Equal(5, solution.ProjectsInOrder.Count);
+
+            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary1\\ClassLibrary1.csproj", false), solution.ProjectsInOrder[0].RelativePath);
+            Assert.Equal("{34E0D07D-CF8F-459D-9449-C4188D8C5564}", solution.ProjectsInOrder[0].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[0].Dependencies);
+            Assert.Null(solution.ProjectsInOrder[0].ParentProjectGuid);
+
+            Assert.Equal("{E0F97730-25D2-418A-A7BD-02CAFDC6E470}", solution.ProjectsInOrder[1].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[1].Dependencies);
+            Assert.Null(solution.ProjectsInOrder[1].ParentProjectGuid);
+
+            Assert.Equal(ConvertToUnixPathIfNeeded("MyPhysicalFolder\\ClassLibrary1\\ClassLibrary1.csproj", false), solution.ProjectsInOrder[2].RelativePath);
+            Assert.Equal("{A5EE8128-B08E-4533-86C5-E46714981680}", solution.ProjectsInOrder[2].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[2].Dependencies);
+            Assert.Equal("{E0F97730-25D2-418A-A7BD-02CAFDC6E470}", solution.ProjectsInOrder[2].ParentProjectGuid);
+
+            Assert.Equal("{2AE8D6C4-FB43-430C-8AEB-15E5EEDAAE4B}", solution.ProjectsInOrder[3].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[3].Dependencies);
+            Assert.Equal("{E0F97730-25D2-418A-A7BD-02CAFDC6E470}", solution.ProjectsInOrder[3].ParentProjectGuid);
+
+            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary2\\ClassLibrary2.csproj", false), solution.ProjectsInOrder[4].RelativePath);
+            Assert.Equal("{6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}", solution.ProjectsInOrder[4].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[4].Dependencies);
+            Assert.Equal("{2AE8D6C4-FB43-430C-8AEB-15E5EEDAAE4B}", solution.ProjectsInOrder[4].ParentProjectGuid);
+        }
+
+        /// <summary>
+        /// Exercises solution folders, and makes sure that samely named projects in different
+        /// solution folders will get correctly uniquified.
+        /// For the new parser, solution folders are not included to ProjectsInOrder or ProjectsByGuid.
+        /// </summary>
+        [Fact]
+        public void SolutionFoldersSlnx()
         {
             string solutionFileContents =
                 """
@@ -266,38 +492,164 @@ public void SolutionFolders(bool convertToSlnx)
                 EndGlobal
                 """;
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, convertToSlnx);
+            SolutionFile solution = ParseSolutionHelper(solutionFileContents, true);
 
             Assert.Equal(3, solution.ProjectsInOrder.Count);
 
             var classLibrary1 = solution.ProjectsInOrder
-                .FirstOrDefault(p => p.RelativePath == ConvertToUnixPathIfNeeded("ClassLibrary1\\ClassLibrary1.csproj"));
+                .FirstOrDefault(p => p.RelativePath == ConvertToUnixPathIfNeeded("ClassLibrary1\\ClassLibrary1.csproj", true));
             Assert.NotNull(classLibrary1);
             Assert.Empty(classLibrary1.Dependencies);
             Assert.Null(classLibrary1.ParentProjectGuid);
 
             var myPhysicalFolderClassLibrary1 = solution.ProjectsInOrder
-                .FirstOrDefault(p => p.RelativePath == ConvertToUnixPathIfNeeded("MyPhysicalFolder\\ClassLibrary1\\ClassLibrary1.csproj"));
+                .FirstOrDefault(p => p.RelativePath == ConvertToUnixPathIfNeeded("MyPhysicalFolder\\ClassLibrary1\\ClassLibrary1.csproj", true));
             Assert.NotNull(myPhysicalFolderClassLibrary1);
             Assert.Empty(myPhysicalFolderClassLibrary1.Dependencies);
 
             var classLibrary2 = solution.ProjectsInOrder
-                .FirstOrDefault(p => p.RelativePath == ConvertToUnixPathIfNeeded("ClassLibrary2\\ClassLibrary2.csproj"));
+                .FirstOrDefault(p => p.RelativePath == ConvertToUnixPathIfNeeded("ClassLibrary2\\ClassLibrary2.csproj", true));
             Assert.NotNull(classLibrary2);
             Assert.Empty(classLibrary2.Dependencies);
 
             // When converting to slnx, the guids are not preserved.
-            if (!convertToSlnx)
+            // try at list assert not null
+            Assert.NotNull(myPhysicalFolderClassLibrary1.ParentProjectGuid);
+            Assert.NotNull(classLibrary2.ParentProjectGuid);
+        }
+
+        /// <summary>
+        /// Exercises shared projects.
+        /// </summary>
+        [Fact]
+        public void SharedProjects()
+        {
+            string solutionFileContents =
+                @"
+                Microsoft Visual Studio Solution File, Format Version 12.00
+                # Visual Studio 15
+                VisualStudioVersion = 15.0.27610.1
+                MinimumVisualStudioVersion = 10.0.40219.1
+                Project('{D954291E-2A0B-460D-934E-DC6B0785DB48}') = 'SharedProject1', 'SharedProject1\SharedProject1.shproj', '{14686F51-D0C2-4832-BBAA-6FBAEC676995}'
+                EndProject
+                Project('{D954291E-2A0B-460D-934E-DC6B0785DB48}') = 'SharedProject2', 'SharedProject2\SharedProject2.shproj', '{BAE750E8-4656-4947-B06B-3961E1051DF7}'
+                EndProject
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{3A0EC360-A42A-417F-BDEF-619682CF6119}'
+                EndProject
+                Project('{F184B08F-C81C-45F6-A57F-5ABD9991F28F}') = 'ClassLibrary2', 'ClassLibrary2\ClassLibrary2.vbproj', '{6DEF6DE8-FBF0-4240-B469-282DEE87899C}'
+                EndProject
+                Global
+                    GlobalSection(SharedMSBuildProjectFiles) = preSolution
+                        SharedProject1\SharedProject1.projitems*{14686f51-d0c2-4832-bbaa-6fbaec676995}*SharedItemsImports = 13
+                        SharedProject1\SharedProject1.projitems*{3a0ec360-a42a-417f-bdef-619682cf6119}*SharedItemsImports = 4
+                        SharedProject2\SharedProject2.projitems*{6def6de8-fbf0-4240-b469-282dee87899c}*SharedItemsImports = 4
+                        SharedProject2\SharedProject2.projitems*{bae750e8-4656-4947-b06b-3961e1051df7}*SharedItemsImports = 13
+                    EndGlobalSection
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|Any CPU = Debug|Any CPU
+                        Release|Any CPU = Release|Any CPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {3A0EC360-A42A-417F-BDEF-619682CF6119}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {3A0EC360-A42A-417F-BDEF-619682CF6119}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                        {3A0EC360-A42A-417F-BDEF-619682CF6119}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                        {3A0EC360-A42A-417F-BDEF-619682CF6119}.Release|Any CPU.Build.0 = Release|Any CPU
+                        {6DEF6DE8-FBF0-4240-B469-282DEE87899C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {6DEF6DE8-FBF0-4240-B469-282DEE87899C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                        {6DEF6DE8-FBF0-4240-B469-282DEE87899C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                        {6DEF6DE8-FBF0-4240-B469-282DEE87899C}.Release|Any CPU.Build.0 = Release|Any CPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                    GlobalSection(ExtensibilityGlobals) = postSolution
+                        SolutionGuid = {1B671EF6-A62A-4497-8351-3EE8679CA86F}
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+            SolutionFile solution = ParseSolutionHelper(solutionFileContents);
+
+            Assert.Equal(4, solution.ProjectsInOrder.Count);
+
+            Assert.Equal(@"SharedProject1\SharedProject1.shproj", solution.ProjectsInOrder[0].RelativePath);
+            Assert.Equal("{14686F51-D0C2-4832-BBAA-6FBAEC676995}", solution.ProjectsInOrder[0].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[0].Dependencies);
+            Assert.Null(solution.ProjectsInOrder[0].ParentProjectGuid);
+
+            Assert.Equal(@"SharedProject2\SharedProject2.shproj", solution.ProjectsInOrder[1].RelativePath);
+            Assert.Equal("{BAE750E8-4656-4947-B06B-3961E1051DF7}", solution.ProjectsInOrder[1].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[1].Dependencies);
+            Assert.Null(solution.ProjectsInOrder[1].ParentProjectGuid);
+
+            Assert.Equal(@"ClassLibrary1\ClassLibrary1.csproj", solution.ProjectsInOrder[2].RelativePath);
+            Assert.Equal("{3A0EC360-A42A-417F-BDEF-619682CF6119}", solution.ProjectsInOrder[2].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[2].Dependencies);
+            Assert.Null(solution.ProjectsInOrder[2].ParentProjectGuid);
+
+            Assert.Equal(@"ClassLibrary2\ClassLibrary2.vbproj", solution.ProjectsInOrder[3].RelativePath);
+            Assert.Equal("{6DEF6DE8-FBF0-4240-B469-282DEE87899C}", solution.ProjectsInOrder[3].ProjectGuid);
+            Assert.Empty(solution.ProjectsInOrder[3].Dependencies);
+            Assert.Null(solution.ProjectsInOrder[3].ParentProjectGuid);
+        }
+
+        /// <summary>
+        /// Tests situation where there's a nonexistent project listed in the solution folders.  We should
+        /// error with a useful message.
+        /// </summary>
+        [Fact]
+        public void MissingNestedProject()
+        {
+            string solutionFileContents =
+                @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{2150E333-8FDC-42A3-9474-1A3956D46DE8}') = 'MySlnFolder', 'MySlnFolder', '{E0F97730-25D2-418A-A7BD-02CAFDC6E470}'
+                EndProject
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'MyPhysicalFolder\ClassLibrary1\ClassLibrary1.csproj', '{A5EE8128-B08E-4533-86C5-E46714981680}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|Any CPU = Debug|Any CPU
+                        Release|Any CPU = Release|Any CPU
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {34E0D07D-CF8F-459D-9449-C4188D8C5564}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {34E0D07D-CF8F-459D-9449-C4188D8C5564}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                        {34E0D07D-CF8F-459D-9449-C4188D8C5564}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                        {34E0D07D-CF8F-459D-9449-C4188D8C5564}.Release|Any CPU.Build.0 = Release|Any CPU
+                        {A5EE8128-B08E-4533-86C5-E46714981680}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {A5EE8128-B08E-4533-86C5-E46714981680}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                        {A5EE8128-B08E-4533-86C5-E46714981680}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                        {A5EE8128-B08E-4533-86C5-E46714981680}.Release|Any CPU.Build.0 = Release|Any CPU
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                        {6DB98C35-FDCC-4818-B5D4-1F0A385FDFD4}.Release|Any CPU.Build.0 = Release|Any CPU
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                    GlobalSection(NestedProjects) = preSolution
+                        {A5EE8128-B08E-4533-86C5-E46714981680} = {E0F97730-25D2-418A-A7BD-02CAFDC6E470}
+                        {2AE8D6C4-FB43-430C-8AEB-15E5EEDAAE4B} = {E0F97730-25D2-418A-A7BD-02CAFDC6E470}
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+            try
             {
-                Assert.Equal("{E0F97730-25D2-418A-A7BD-02CAFDC6E470}", myPhysicalFolderClassLibrary1.ParentProjectGuid);
-                Assert.Equal("{2AE8D6C4-FB43-430C-8AEB-15E5EEDAAE4B}", classLibrary2.ParentProjectGuid);
+                ParseSolutionHelper(solutionFileContents);
             }
-            else
+            catch (InvalidProjectFileException e)
             {
-                // try at least assert not null
-                Assert.NotNull(myPhysicalFolderClassLibrary1.ParentProjectGuid);
-                Assert.NotNull(classLibrary2.ParentProjectGuid);
+                Assert.Equal("MSB5023", e.ErrorCode);
+                Assert.Contains("{2AE8D6C4-FB43-430C-8AEB-15E5EEDAAE4B}", e.Message);
+                return;
             }
+
+            // Should not get here
+            Assert.Fail();
         }
 
         /// <summary>
@@ -359,19 +711,19 @@ public void SolutionDependencies(bool convertToSlnx)
             var classLibrary2 = solution.ProjectsInOrder.First(p => p.ProjectName == "ClassLibrary2");
             var classLibrary3 = solution.ProjectsInOrder.First(p => p.ProjectName == "ClassLibrary3");
 
-            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary1\\ClassLibrary1.csproj"), classLibrary1.RelativePath);
+            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary1\\ClassLibrary1.csproj", convertToSlnx), classLibrary1.RelativePath);
             Assert.Single(classLibrary1.Dependencies);
             Assert.Equal(classLibrary3.ProjectGuid, classLibrary1.Dependencies[0]);
             Assert.Null(solution.ProjectsInOrder[0].ParentProjectGuid);
 
-            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary2\\ClassLibrary2.csproj"), classLibrary2.RelativePath);
+            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary2\\ClassLibrary2.csproj", convertToSlnx), classLibrary2.RelativePath);
             Assert.Equal(2, classLibrary2.Dependencies.Count);
             // When converting to SLNX, the projects dependencies order is not preserved.
             Assert.Contains(classLibrary3.ProjectGuid, classLibrary2.Dependencies);
             Assert.Contains(classLibrary1.ProjectGuid, classLibrary2.Dependencies);
             Assert.Null(solution.ProjectsInOrder[1].ParentProjectGuid);
 
-            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary3\\ClassLibrary3.csproj"), solution.ProjectsInOrder[2].RelativePath);
+            Assert.Equal(ConvertToUnixPathIfNeeded("ClassLibrary3\\ClassLibrary3.csproj", convertToSlnx), solution.ProjectsInOrder[2].RelativePath);
             Assert.Empty(solution.ProjectsInOrder[2].Dependencies);
             Assert.Null(solution.ProjectsInOrder[2].ParentProjectGuid);
         }
@@ -515,6 +867,85 @@ public void ParseSolutionConfigurationsNoMixedPlatform(bool convertToSlnx)
             Assert.Equal("Any CPU", solution.GetDefaultPlatformName()); // "Default solution platform"
         }
 
+        /// <summary>
+        /// Test some invalid cases for solution configuration parsing.
+        /// There can be only one '=' character in a sln cfg entry, separating two identical names
+        /// </summary>
+        [Fact]
+        public void ParseInvalidSolutionConfigurations1()
+        {
+            Assert.Throws<InvalidProjectFileException>(() =>
+            {
+                string solutionFileContents =
+                    @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|Any=CPU = Debug|Any=CPU
+                        Release|Any CPU = Release|Any CPU
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+                ParseSolutionHelper(solutionFileContents);
+            });
+        }
+        /// <summary>
+        /// Test some invalid cases for solution configuration parsing
+        /// There can be only one '=' character in a sln cfg entry, separating two identical names
+        /// </summary>
+        [Fact]
+        public void ParseInvalidSolutionConfigurations2()
+        {
+            Assert.Throws<InvalidProjectFileException>(() =>
+            {
+                string solutionFileContents =
+                    @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|Any CPU = Something|Else
+                        Release|Any CPU = Release|Any CPU
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+                ParseSolutionHelper(solutionFileContents);
+            });
+        }
+        /// <summary>
+        /// Test some invalid cases for solution configuration parsing
+        /// Solution configurations must include the platform part
+        /// </summary>
+        [Fact]
+        public void ParseInvalidSolutionConfigurations3()
+        {
+            Assert.Throws<InvalidProjectFileException>(() =>
+            {
+                string solutionFileContents =
+                    @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug = Debug
+                        Release|Any CPU = Release|Any CPU
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+                ParseSolutionHelper(solutionFileContents);
+            });
+        }
+
         /// <summary>
         /// Make sure the project configurations in solution configurations get parsed correctly
         /// for a simple mixed C#/VC solution
@@ -615,10 +1046,69 @@ public void ParseProjectConfigurationsInSolutionConfigurations1(bool convertToSl
             Assert.True(vcProject.ProjectConfigurations["Release|Win32"].IncludeInBuild);
         }
 
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void ParseProjectConfigurationsInSolutionConfigurations2(bool convertToSlnx)
+        /// <summary>
+        /// Make sure the project configurations in solution configurations get parsed correctly
+        /// for a more tricky solution
+        /// </summary>
+        [Fact]
+        public void ParseProjectConfigurationsInSolutionConfigurations2()
+        {
+            string solutionFileContents =
+                @"
+                Microsoft Visual Studio Solution File, Format Version 9.00
+                # Visual Studio 2005
+                Project('{E24C65DC-7377-472B-9ABA-BC803B73C61A}') = 'C:\solutions\WebSite1\', '..\WebSite1\', '{E8E75132-67E4-4D6F-9CAE-8DA4C883F418}'
+                EndProject
+                Project('{E24C65DC-7377-472B-9ABA-BC803B73C61A}') = 'C:\solutions\WebSite2\', '..\WebSite2\', '{E8E75132-67E4-4D6F-9CAE-8DA4C883F419}'
+                EndProject
+                Project('{2150E333-8FDC-42A3-9474-1A3956D46DE8}') = 'NewFolder1', 'NewFolder1', '{54D20FFE-84BE-4066-A51E-B25D040A4235}'
+                EndProject
+                Project('{2150E333-8FDC-42A3-9474-1A3956D46DE8}') = 'NewFolder2', 'NewFolder2', '{D2633E4D-46FF-4C4E-8340-4BC7CDF78615}'
+                EndProject
+                Project('{8BC9CEB9-8B4A-11D0-8D11-00A0C91BC942}') = 'MSBuild.exe', '..\..\dd\binaries.x86dbg\bin\i386\MSBuild.exe', '{25FD9E7C-F37E-48E0-9A7C-607FE4AACCC0}'
+                EndProject
+                Global
+                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                        Debug|.NET = Debug|.NET
+                    EndGlobalSection
+                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                        {E8E75132-67E4-4D6F-9CAE-8DA4C883F418}.Debug|.NET.ActiveCfg = Debug|.NET
+                        {E8E75132-67E4-4D6F-9CAE-8DA4C883F418}.Debug|.NET.Build.0 = Debug|.NET
+                        {25FD9E7C-F37E-48E0-9A7C-607FE4AACCC0}.Debug|.NET.ActiveCfg = Debug
+                    EndGlobalSection
+                    GlobalSection(SolutionProperties) = preSolution
+                        HideSolutionNode = FALSE
+                    EndGlobalSection
+                    GlobalSection(NestedProjects) = preSolution
+                        {25FD9E7C-F37E-48E0-9A7C-607FE4AACCC0} = {D2633E4D-46FF-4C4E-8340-4BC7CDF78615}
+                    EndGlobalSection
+                EndGlobal
+                ";
+
+            SolutionFile solution = ParseSolutionHelper(solutionFileContents);
+
+            ProjectInSolution webProject = (ProjectInSolution)solution.ProjectsByGuid["{E8E75132-67E4-4D6F-9CAE-8DA4C883F418}"];
+            ProjectInSolution exeProject = (ProjectInSolution)solution.ProjectsByGuid["{25FD9E7C-F37E-48E0-9A7C-607FE4AACCC0}"];
+            ProjectInSolution missingWebProject = (ProjectInSolution)solution.ProjectsByGuid["{E8E75132-67E4-4D6F-9CAE-8DA4C883F419}"];
+
+            Assert.Single(webProject.ProjectConfigurations);
+
+            Assert.Equal("Debug|.NET", webProject.ProjectConfigurations["Debug|.NET"].FullName);
+            Assert.True(webProject.ProjectConfigurations["Debug|.NET"].IncludeInBuild);
+
+            Assert.Single(exeProject.ProjectConfigurations);
+
+            Assert.Equal("Debug", exeProject.ProjectConfigurations["Debug|.NET"].FullName);
+            Assert.False(exeProject.ProjectConfigurations["Debug|.NET"].IncludeInBuild);
+
+            Assert.Empty(missingWebProject.ProjectConfigurations);
+
+            Assert.Equal("Debug", solution.GetDefaultConfigurationName()); // "Default solution configuration"
+            Assert.Equal(".NET", solution.GetDefaultPlatformName()); // "Default solution platform"
+        }
+
+        [Fact]
+        public void ParseProjectConfigurationsInSolutionConfigurationsSlnx()
         {
             string solutionFileContents =
                 """
@@ -654,7 +1144,7 @@ public void ParseProjectConfigurationsInSolutionConfigurations2(bool convertToSl
                 EndGlobal
                 """;
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, convertToSlnx);
+            SolutionFile solution = ParseSolutionHelper(solutionFileContents, true);
 
             ProjectInSolution winFormsApp1 = solution.ProjectsInOrder.First(p => p.ProjectName == "WinFormsApp1");
             ProjectInSolution classLibrary1 = solution.ProjectsInOrder.First(p => p.ProjectName == "ClassLibrary1");
@@ -676,6 +1166,59 @@ public void ParseProjectConfigurationsInSolutionConfigurations2(bool convertToSl
             Assert.False(classLibrary1.ProjectConfigurations["Release|Any CPU"].IncludeInBuild);
         }
 
+        /// <summary>
+        /// Parse solution file with comments
+        /// </summary>
+        [Fact]
+        public void ParseSolutionWithComments()
+        {
+            const string solutionFileContent = @"
+                    Microsoft Visual Studio Solution File, Format Version 12.00
+                    # Visual Studio Version 16
+                    VisualStudioVersion = 16.0.29123.89
+                    MinimumVisualStudioVersion = 10.0.40219.1
+                    Project('{9A19103F-16F7-4668-BE54-9A1E7A4F7556}') = 'SlnCommentTest', 'SlnCommentTest.csproj', '{00000000-0000-0000-FFFF-FFFFFFFFFFFF}'
+                    EndProject
+                    Project('{2150E333-8FDC-42A3-9474-1A3956D46DE8}') = 'Solution Items', 'Solution Items', '{054DED3B-B890-4652-B449-839F581E5D86}'
+	                    ProjectSection(SolutionItems) = preProject
+		                    SlnFile.txt = SlnFile.txt
+	                    EndProjectSection
+                    EndProject
+                    Global
+	                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		                    Debug|Any CPU = Debug|Any CPU
+		                    Release|Any CPU = Release|Any CPU
+	                    EndGlobalSection
+	                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		                    {00000000-0000-0000-FFFF-FFFFFFFFFFFF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		                    {00000000-0000-0000-FFFF-FFFFFFFFFFFF}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		                    {00000000-0000-0000-FFFF-FFFFFFFFFFFF}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		                    {00000000-0000-0000-FFFF-FFFFFFFFFFFF}.Release|Any CPU.Build.0 = Release|Any CPU
+	                    EndGlobalSection
+	                    GlobalSection(SolutionProperties) = preSolution
+		                    HideSolutionNode = FALSE
+	                    EndGlobalSection
+	                    GlobalSection(ExtensibilityGlobals) = postSolution
+		                    SolutionGuid = {FFFFFFFF-FFFF-FFFF-0000-000000000000}
+	                    EndGlobalSection
+                    EndGlobal
+                    ";
+
+            StringBuilder stringBuilder = new StringBuilder();
+
+            // Put comment between all lines
+            const string comment = "\t# comment";
+            string[] lines = solutionFileContent.Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
+            for (int i = 0; i < lines.Length; i++)
+            {
+                stringBuilder.AppendLine(comment);
+                stringBuilder.AppendLine(lines[i]);
+            }
+            stringBuilder.AppendLine(comment);
+
+            Should.NotThrow(() => ParseSolutionHelper(stringBuilder.ToString()));
+        }
+
         /// <summary>
         /// Helper method to create a SolutionFile object, and call it to parse the SLN file
         /// represented by the string contents passed in. Optionally can convert the SLN to SLNX and then parse the solution.
@@ -703,10 +1246,11 @@ private static string ConvertToSlnx(string slnPath)
             return slnxPath;
         }
 
-        private static string ConvertToUnixPathIfNeeded(string path)
+        private static string ConvertToUnixPathIfNeeded(string path, bool isConvertedToSlnx)
         {
             // In the new parser, ProjectModel.FilePath is converted to Unix-style.
-            return !NativeMethodsShared.IsWindows ? path.Replace('\\', '/') : path;
+            // we are using the new parser only for slnx files.
+            return !NativeMethodsShared.IsWindows && isConvertedToSlnx ? path.Replace('\\', '/') : path;
         }
     }
 }
diff --git a/src/Build.UnitTests/Construction/ProjectRootElement_Tests.cs b/src/Build.UnitTests/Construction/ProjectRootElement_Tests.cs
index 7b98b820a4f..13ab48079a4 100644
--- a/src/Build.UnitTests/Construction/ProjectRootElement_Tests.cs
+++ b/src/Build.UnitTests/Construction/ProjectRootElement_Tests.cs
@@ -5,6 +5,7 @@
 using System;
 using System.Text;
 using Microsoft.Build.Construction;
+using Microsoft.Build.Evaluation;
 using Xunit;
 
 #nullable disable
@@ -116,5 +117,16 @@ public void ProjectLoadedStrippingCommentsAndWhiteSpaceIsReadOnly()
                 Assert.Equal(string.Empty, children[0].ChildNodes[1].Value);
             }
         }
+
+        [Fact]
+        public void CreateEphemeralCannotBeDirtied()
+        {
+            var projectRootElement = ProjectRootElement.CreateEphemeral(ProjectCollection.GlobalProjectCollection.ProjectRootElementCache);
+            var versionBeforeMarkDirty = projectRootElement.Version;
+
+            projectRootElement.MarkDirty("test", "test");
+
+            Assert.Equal(projectRootElement.Version, versionBeforeMarkDirty);
+        }
     }
 }
diff --git a/src/Build.UnitTests/Construction/SolutionFile_OldParser_Tests.cs b/src/Build.UnitTests/Construction/SolutionFile_Tests.cs
similarity index 95%
rename from src/Build.UnitTests/Construction/SolutionFile_OldParser_Tests.cs
rename to src/Build.UnitTests/Construction/SolutionFile_Tests.cs
index ab51906b222..79bb93a4703 100644
--- a/src/Build.UnitTests/Construction/SolutionFile_OldParser_Tests.cs
+++ b/src/Build.UnitTests/Construction/SolutionFile_Tests.cs
@@ -5,7 +5,6 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.IO;
-using System.Text;
 using Microsoft.Build.Construction;
 using Microsoft.Build.Exceptions;
 using Microsoft.Build.Shared;
@@ -17,11 +16,11 @@
 
 namespace Microsoft.Build.UnitTests.Construction
 {
-    public class SolutionFile_OldParser_Tests
+    public class SolutionFile_Tests
     {
         public ITestOutputHelper TestOutputHelper { get; }
 
-        public SolutionFile_OldParser_Tests(ITestOutputHelper testOutputHelper)
+        public SolutionFile_Tests(ITestOutputHelper testOutputHelper)
         {
             TestOutputHelper = testOutputHelper;
         }
@@ -105,42 +104,6 @@ public void ParseFirstProjectLineWithDifferentSpacing()
             proj.ProjectGuid.ShouldBe("Unique name-GUID");
         }
 
-        /// <summary>
-        /// A slightly more complicated test where there is some different whitespace.
-        /// </summary>
-        [Fact]
-        public void ParseSolutionWithDifferentSpacing()
-        {
-            string solutionFileContents =
-                @"
-                Microsoft Visual Studio Solution File, Format Version 9.00
-                # Visual Studio 2005
-                Project(' { Project GUID} ')  = ' Project name ',  ' Relative path to project file '    , ' {0ABED153-9451-483C-8140-9E8D7306B216} '
-                EndProject
-                Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|AnyCPU = Debug|AnyCPU
-                        Release|AnyCPU = Release|AnyCPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.ActiveCfg = Debug|AnyCPU
-                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.Build.0 = Debug|AnyCPU
-                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.ActiveCfg = Release|AnyCPU
-                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.Build.0 = Release|AnyCPU
-                    EndGlobalSection
-                    GlobalSection(SolutionProperties) = preSolution
-                        HideSolutionNode = FALSE
-                    EndGlobalSection
-                EndGlobal
-                ";
-
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents);
-
-            Assert.Equal("Project name", solution.ProjectsInOrder[0].ProjectName);
-            Assert.Equal("Relative path to project file", solution.ProjectsInOrder[0].RelativePath);
-            Assert.Equal("{0ABED153-9451-483C-8140-9E8D7306B216}", solution.ProjectsInOrder[0].ProjectGuid);
-        }
-
         /// <summary>
         /// First project line with an empty project name.  This is somewhat malformed, but we should
         /// still behave reasonably instead of crashing.
@@ -724,43 +687,6 @@ public void ParseFirstProjectLineWhereProjectNameHasSpecialCharacters()
             proj.ProjectGuid.ShouldBe("Unique name-GUID");
         }
 
-        /// <summary>
-        /// Test some characters that are valid in a file name but that also could be
-        /// considered a delimiter by a parser. Does quoting work for special characters?
-        /// </summary>
-        [Fact]
-        public void ParseSolutionWhereProjectNameHasSpecialCharacters()
-        {
-            string solutionFileContents =
-                           @"
-                Microsoft Visual Studio Solution File, Format Version 9.00
-                # Visual Studio 2005
-                Project('{Project GUID}')  = 'MyProject,(=IsGreat)',  'Relative path to project file'    , '{0ABED153-9451-483C-8140-9E8D7306B216}'
-                EndProject
-                Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|AnyCPU = Debug|AnyCPU
-                        Release|AnyCPU = Release|AnyCPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.ActiveCfg = Debug|AnyCPU
-                        {0ABED153-9451-483C-8140-9E8D7306B216}.Debug|AnyCPU.Build.0 = Debug|AnyCPU
-                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.ActiveCfg = Release|AnyCPU
-                        {0ABED153-9451-483C-8140-9E8D7306B216}.Release|AnyCPU.Build.0 = Release|AnyCPU
-                    EndGlobalSection
-                    GlobalSection(SolutionProperties) = preSolution
-                        HideSolutionNode = FALSE
-                    EndGlobalSection
-                EndGlobal
-                ";
-
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents);
-
-            Assert.Equal("MyProject,(=IsGreat)", solution.ProjectsInOrder[0].ProjectName);
-            Assert.Equal("Relative path to project file", solution.ProjectsInOrder[0].RelativePath);
-            Assert.Equal("{0ABED153-9451-483C-8140-9E8D7306B216}", solution.ProjectsInOrder[0].ProjectGuid);
-        }
-
         /// <summary>
         /// Test some characters that are valid in a file name but that also could be
         /// considered a delimiter by a parser. Does quoting work for special characters?
@@ -2429,58 +2355,5 @@ public void ParseSolutionWithParentedPaths()
             solution.ProjectsInOrder[0].AbsolutePath.ShouldBe(Path.GetFullPath(Path.Combine(Path.GetDirectoryName(solution.FullPath)!, expectedRelativePath)));
             solution.ProjectsInOrder[0].ProjectGuid.ShouldBe("{0ABED153-9451-483C-8140-9E8D7306B216}");
         }
-
-        /// <summary>
-        /// Parse solution file with comments
-        /// </summary>
-        [Fact]
-        public void ParseSolutionWithComments()
-        {
-            const string solutionFileContent = @"
-                    Microsoft Visual Studio Solution File, Format Version 12.00
-                    # Visual Studio Version 16
-                    VisualStudioVersion = 16.0.29123.89
-                    MinimumVisualStudioVersion = 10.0.40219.1
-                    Project('{9A19103F-16F7-4668-BE54-9A1E7A4F7556}') = 'SlnCommentTest', 'SlnCommentTest.csproj', '{00000000-0000-0000-FFFF-FFFFFFFFFFFF}'
-                    EndProject
-                    Project('{2150E333-8FDC-42A3-9474-1A3956D46DE8}') = 'Solution Items', 'Solution Items', '{054DED3B-B890-4652-B449-839F581E5D86}'
-	                    ProjectSection(SolutionItems) = preProject
-		                    SlnFile.txt = SlnFile.txt
-	                    EndProjectSection
-                    EndProject
-                    Global
-	                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		                    Debug|Any CPU = Debug|Any CPU
-		                    Release|Any CPU = Release|Any CPU
-	                    EndGlobalSection
-	                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		                    {00000000-0000-0000-FFFF-FFFFFFFFFFFF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		                    {00000000-0000-0000-FFFF-FFFFFFFFFFFF}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		                    {00000000-0000-0000-FFFF-FFFFFFFFFFFF}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		                    {00000000-0000-0000-FFFF-FFFFFFFFFFFF}.Release|Any CPU.Build.0 = Release|Any CPU
-	                    EndGlobalSection
-	                    GlobalSection(SolutionProperties) = preSolution
-		                    HideSolutionNode = FALSE
-	                    EndGlobalSection
-	                    GlobalSection(ExtensibilityGlobals) = postSolution
-		                    SolutionGuid = {FFFFFFFF-FFFF-FFFF-0000-000000000000}
-	                    EndGlobalSection
-                    EndGlobal
-                    ";
-
-            StringBuilder stringBuilder = new StringBuilder();
-
-            // Put comment between all lines
-            const string comment = "\t# comment";
-            string[] lines = solutionFileContent.Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
-            for (int i = 0; i < lines.Length; i++)
-            {
-                stringBuilder.AppendLine(comment);
-                stringBuilder.AppendLine(lines[i]);
-            }
-            stringBuilder.AppendLine(comment);
-
-            Should.NotThrow(() => ParseSolutionHelper(stringBuilder.ToString()));
-        }
     }
 }
diff --git a/src/Build.UnitTests/Construction/SolutionFilter_Tests.cs b/src/Build.UnitTests/Construction/SolutionFilter_Tests.cs
index 6d2a8f9ad1a..98f25d366cc 100644
--- a/src/Build.UnitTests/Construction/SolutionFilter_Tests.cs
+++ b/src/Build.UnitTests/Construction/SolutionFilter_Tests.cs
@@ -72,14 +72,14 @@ public void SolutionFilterFiltersProjects(bool graphBuild)
                     ");
                 // Slashes here (and in the .slnf) are hardcoded as backslashes intentionally to support the common case.
                 TransientTestFile solutionFile = testEnvironment.CreateFile(simpleProjectFolder, "SimpleProject.sln",
-                    """
+                    @"
                     Microsoft Visual Studio Solution File, Format Version 12.00
                     # Visual Studio Version 16
                     VisualStudioVersion = 16.0.29326.124
                     MinimumVisualStudioVersion = 10.0.40219.1
-                    Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SimpleProject", "SimpleProject\SimpleProject.csproj", "{79B5EBA6-5D27-4976-BC31-14422245A59A}"
+                    Project(""{9A19103F-16F7-4668-BE54-9A1E7A4F7556}"") = ""SimpleProject"", ""SimpleProject\SimpleProject.csproj"", ""{79B5EBA6-5D27-4976-BC31-14422245A59A}""
                     EndProject
-                    Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ClassLibrary", "..\ClassLibrary\ClassLibrary\ClassLibrary.csproj", "{8EFCCA22-9D51-4268-90F7-A595E11FCB2D}"
+                    Project(""{9A19103F-16F7-4668-BE54-9A1E7A4F7556}"") = ""ClassLibrary"", ""..\ClassLibrary\ClassLibrary\ClassLibrary.csproj"", ""{8EFCCA22-9D51-4268-90F7-A595E11FCB2D}""
                     EndProject
                     Global
                         GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -107,7 +107,7 @@ public void SolutionFilterFiltersProjects(bool graphBuild)
                             SolutionGuid = {DE7234EC-0C4D-4070-B66A-DCF1B4F0CFEF}
                         EndGlobalSection
                     EndGlobal
-                    """);
+                ");
                 TransientTestFile filterFile = testEnvironment.CreateFile(folder, "solutionFilter.slnf",
                     /*lang=json*/
                                   """
diff --git a/src/Build.UnitTests/Construction/SolutionProjectGenerator_Tests.cs b/src/Build.UnitTests/Construction/SolutionProjectGenerator_Tests.cs
index cd359a54c8b..8e28604557b 100644
--- a/src/Build.UnitTests/Construction/SolutionProjectGenerator_Tests.cs
+++ b/src/Build.UnitTests/Construction/SolutionProjectGenerator_Tests.cs
@@ -38,8 +38,6 @@ public class SolutionProjectGenerator_Tests : IDisposable
 
         private static readonly BuildEventContext _buildEventContext = new BuildEventContext(0, 0, BuildEventContext.InvalidProjectContextId, 0);
 
-        private const string _longLineString = "a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-";
-
         public SolutionProjectGenerator_Tests(ITestOutputHelper output)
         {
             this.output = output;
@@ -67,14 +65,12 @@ public void SolutionProjectIgnoresDuplicateDefaultTargets(string name)
             using (TestEnvironment testEnvironment = TestEnvironment.Create())
             {
                 TransientTestFolder folder = testEnvironment.CreateFolder(createFolder: true);
-                TransientTestFile sln = testEnvironment.CreateFile(folder, "MySln.sln", "Microsoft Visual Studio Solution File, Format Version 12.00");
+                TransientTestFile sln = testEnvironment.CreateFile(folder, "MySln.sln", @"Microsoft Visual Studio Solution File, Format Version 16.00");
                 TransientTestFile targetsFile = testEnvironment.CreateFile(folder, name,
-                      """
-                      <Project>
-                        <Target Name="Build" AfterTargets="NonsenseTarget">
+                    @"<Project>
+                        <Target Name=""Build"" AfterTargets=""NonsenseTarget"">
                         </Target>
-                      </Project>
-                      """);
+                      </Project>");
                 ProjectInstance[] instances = SolutionProjectGenerator.Generate(SolutionFile.Parse(sln.Path), null, null, _buildEventContext, CreateMockLoggingService());
                 instances.ShouldHaveSingleItem();
                 instances[0].Targets["Build"].AfterTargets.ShouldBe(string.Empty);
@@ -91,35 +87,33 @@ public void BuildProjectAsTarget()
                 TransientTestFolder folder = testEnvironment.CreateFolder(createFolder: true);
                 TransientTestFolder classLibFolder = testEnvironment.CreateFolder(Path.Combine(folder.Path, "classlib"), createFolder: true);
                 TransientTestFile classLibrary = testEnvironment.CreateFile(classLibFolder, "classlib.csproj",
-                  """
-                  <Project>
-                  <Target Name="ClassLibraryTarget">
-                      <Message Text="ClassLibraryBuilt"/>
+                    @"<Project>
+                  <Target Name=""ClassLibraryTarget"">
+                      <Message Text=""ClassLibraryBuilt""/>
                   </Target>
                   </Project>
-                  """);
+                    ");
 
                 TransientTestFolder simpleProjectFolder = testEnvironment.CreateFolder(Path.Combine(folder.Path, "simpleProject"), createFolder: true);
                 TransientTestFile simpleProject = testEnvironment.CreateFile(simpleProjectFolder, "simpleProject.csproj",
-                  """
-                  <Project>
-                  <Target Name="SimpleProjectTarget">
-                      <Message Text="SimpleProjectBuilt"/>
+                    @"<Project>
+                  <Target Name=""SimpleProjectTarget"">
+                      <Message Text=""SimpleProjectBuilt""/>
                   </Target>
                   </Project>
-                  """);
+                    ");
 
                 TransientTestFile solutionFile = testEnvironment.CreateFile(folder, "testFolder.sln",
-                    """
-                    Microsoft Visual Studio Solution File, Format Version 12.00
-                    # Visual Studio Version 16
-                    VisualStudioVersion = 16.6.30114.105
-                    MinimumVisualStudioVersion = 10.0.40219.1
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "simpleProject", "simpleProject\simpleProject.csproj", "{AA52A05F-A9C0-4C89-9933-BF976A304C91}"
-                    EndProject
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "classlib", "classlib\classlib.csproj", "{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}"
-                    EndProject
-                    """);
+                    @"
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.6.30114.105
+MinimumVisualStudioVersion = 10.0.40219.1
+Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""simpleProject"", ""simpleProject\simpleProject.csproj"", ""{AA52A05F-A9C0-4C89-9933-BF976A304C91}""
+EndProject
+Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""classlib"", ""classlib\classlib.csproj"", ""{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}""
+EndProject
+                ");
                 RunnerUtilities.ExecMSBuild(solutionFile.Path + " /t:classlib", out bool success);
                 success.ShouldBeTrue();
             }
@@ -136,58 +130,56 @@ public void BuildProjectWithMultipleTargets()
                 TransientTestFolder folder = testEnvironment.CreateFolder(createFolder: true);
                 TransientTestFolder classLibFolder = testEnvironment.CreateFolder(Path.Combine(folder.Path, "classlib"), createFolder: true);
                 TransientTestFile classLibrary = testEnvironment.CreateFile(classLibFolder, "classlib.csproj",
-                  """
-                  <Project>
-                  <Target Name="Build">
-                      <Message Text="classlib.Build"/>
+                    @"<Project>
+                  <Target Name=""Build"">
+                      <Message Text=""classlib.Build""/>
                   </Target>
-                  <Target Name="Clean">
-                      <Message Text="classlib.Clean"/>
+                  <Target Name=""Clean"">
+                      <Message Text=""classlib.Clean""/>
                   </Target>
-                  <Target Name="Custom">
-                      <Message Text="classlib.Custom"/>
+                  <Target Name=""Custom"">
+                      <Message Text=""classlib.Custom""/>
                   </Target>
                   </Project>
-                  """);
+                    ");
 
                 TransientTestFolder simpleProjectFolder = testEnvironment.CreateFolder(Path.Combine(folder.Path, "simpleProject"), createFolder: true);
                 TransientTestFile simpleProject = testEnvironment.CreateFile(simpleProjectFolder, "simpleProject.csproj",
-                  """
-                  <Project>
-                  <Target Name="Build">
-                      <Message Text="simpleProject.Build"/>
+                    @"<Project>
+                  <Target Name=""Build"">
+                      <Message Text=""simpleProject.Build""/>
                   </Target>
-                  <Target Name="Clean">
-                      <Message Text="simpleProject.Clean"/>
+                  <Target Name=""Clean"">
+                      <Message Text=""simpleProject.Clean""/>
                   </Target>
-                  <Target Name="Custom">
-                      <Message Text="simpleProject.Custom"/>
+                  <Target Name=""Custom"">
+                      <Message Text=""simpleProject.Custom""/>
                   </Target>
                   </Project>
-                  """);
+                    ");
 
                 TransientTestFile solutionFile = testEnvironment.CreateFile(folder, "testFolder.sln",
-                    """
-                    Microsoft Visual Studio Solution File, Format Version 12.00
-                    # Visual Studio Version 16
-                    VisualStudioVersion = 16.6.30114.105
-                    MinimumVisualStudioVersion = 10.0.40219.1
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "simpleProject", "simpleProject\simpleProject.csproj", "{AA52A05F-A9C0-4C89-9933-BF976A304C91}"
-                    EndProject
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "classlib", "classlib\classlib.csproj", "{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}"
-                    EndProject
-                    Global
-                        GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                            Debug|x86 = Debug|x86
-                        EndGlobalSection
-                        GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                            {AA52A05F-A9C0-4C89-9933-BF976A304C91}.Debug|x86.ActiveCfg = Debug|x86
-                            {AA52A05F-A9C0-4C89-9933-BF976A304C91}.Debug|x86.Build.0 = Debug|x86
-                            {80B8E6B8-E46D-4456-91B1-848FD35C4AB9}.Debug|x86.ActiveCfg = Debug|x86
-                            {80B8E6B8-E46D-4456-91B1-848FD35C4AB9}.Debug|x86.Build.0 = Debug|x86
-                        EndGlobalSection
-                        EndGlobal
-                    """);
+                    @"
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.6.30114.105
+MinimumVisualStudioVersion = 10.0.40219.1
+Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""simpleProject"", ""simpleProject\simpleProject.csproj"", ""{AA52A05F-A9C0-4C89-9933-BF976A304C91}""
+EndProject
+Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""classlib"", ""classlib\classlib.csproj"", ""{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}""
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|x86 = Debug|x86
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{AA52A05F-A9C0-4C89-9933-BF976A304C91}.Debug|x86.ActiveCfg = Debug|x86
+		{AA52A05F-A9C0-4C89-9933-BF976A304C91}.Debug|x86.Build.0 = Debug|x86
+		{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}.Debug|x86.ActiveCfg = Debug|x86
+		{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}.Debug|x86.Build.0 = Debug|x86
+	EndGlobalSection
+EndGlobal
+                ");
 
                 string output = RunnerUtilities.ExecMSBuild(solutionFile.Path + " /t:Clean;Build;Custom", out bool success);
                 success.ShouldBeTrue();
@@ -212,58 +204,56 @@ public void BuildProjectWithMultipleTargetsInParallel()
                 TransientTestFolder folder = testEnvironment.CreateFolder(createFolder: true);
                 TransientTestFolder classLibFolder = testEnvironment.CreateFolder(Path.Combine(folder.Path, "classlib"), createFolder: true);
                 TransientTestFile classLibrary = testEnvironment.CreateFile(classLibFolder, "classlib.csproj",
-                  """
-                  <Project>
-                  <Target Name="Build">
-                      <Message Text="classlib.Build"/>
+                    @"<Project>
+                  <Target Name=""Build"">
+                      <Message Text=""classlib.Build""/>
                   </Target>
-                  <Target Name="Clean">
-                      <Message Text="classlib.Clean"/>
+                  <Target Name=""Clean"">
+                      <Message Text=""classlib.Clean""/>
                   </Target>
-                  <Target Name="Custom">
-                      <Message Text="classlib.Custom"/>
+                  <Target Name=""Custom"">
+                      <Message Text=""classlib.Custom""/>
                   </Target>
                   </Project>
-                  """);
+                    ");
 
                 TransientTestFolder simpleProjectFolder = testEnvironment.CreateFolder(Path.Combine(folder.Path, "simpleProject"), createFolder: true);
                 TransientTestFile simpleProject = testEnvironment.CreateFile(simpleProjectFolder, "simpleProject.csproj",
-                  """
-                  <Project>
-                  <Target Name="Build">
-                      <Message Text="simpleProject.Build"/>
+                    @"<Project>
+                  <Target Name=""Build"">
+                      <Message Text=""simpleProject.Build""/>
                   </Target>
-                  <Target Name="Clean">
-                      <Message Text="simpleProject.Clean"/>
+                  <Target Name=""Clean"">
+                      <Message Text=""simpleProject.Clean""/>
                   </Target>
-                  <Target Name="Custom">
-                      <Message Text="simpleProject.Custom"/>
+                  <Target Name=""Custom"">
+                      <Message Text=""simpleProject.Custom""/>
                   </Target>
                   </Project>
-                  """);
+                    ");
 
                 TransientTestFile solutionFile = testEnvironment.CreateFile(folder, "testFolder.sln",
-                    """
-                    Microsoft Visual Studio Solution File, Format Version 12.00
-                    # Visual Studio Version 16
-                    VisualStudioVersion = 16.6.30114.105
-                    MinimumVisualStudioVersion = 10.0.40219.1
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "simpleProject", "simpleProject\simpleProject.csproj", "{AA52A05F-A9C0-4C89-9933-BF976A304C91}"
-                    EndProject
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "classlib", "classlib\classlib.csproj", "{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}"
-                    EndProject
-                    Global
-                        GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                            Debug|x86 = Debug|x86
-                        EndGlobalSection
-                        GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                            {AA52A05F-A9C0-4C89-9933-BF976A304C91}.Debug|x86.ActiveCfg = Debug|x86
-                            {AA52A05F-A9C0-4C89-9933-BF976A304C91}.Debug|x86.Build.0 = Debug|x86
-                            {80B8E6B8-E46D-4456-91B1-848FD35C4AB9}.Debug|x86.ActiveCfg = Debug|x86
-                            {80B8E6B8-E46D-4456-91B1-848FD35C4AB9}.Debug|x86.Build.0 = Debug|x86
-                        EndGlobalSection
-                    EndGlobal
-                    """);
+                    @"
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.6.30114.105
+MinimumVisualStudioVersion = 10.0.40219.1
+Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""simpleProject"", ""simpleProject\simpleProject.csproj"", ""{AA52A05F-A9C0-4C89-9933-BF976A304C91}""
+EndProject
+Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""classlib"", ""classlib\classlib.csproj"", ""{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}""
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|x86 = Debug|x86
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{AA52A05F-A9C0-4C89-9933-BF976A304C91}.Debug|x86.ActiveCfg = Debug|x86
+		{AA52A05F-A9C0-4C89-9933-BF976A304C91}.Debug|x86.Build.0 = Debug|x86
+		{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}.Debug|x86.ActiveCfg = Debug|x86
+		{80B8E6B8-E46D-4456-91B1-848FD35C4AB9}.Debug|x86.Build.0 = Debug|x86
+	EndGlobalSection
+EndGlobal
+                ");
 
                 try
                 {
@@ -341,12 +331,10 @@ public void AddNewErrorWarningMessageElement()
         /// Test to make sure we properly set the ToolsVersion attribute on the in-memory project based
         /// on the Solution File Format Version.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void EmitToolsVersionAttributeToInMemoryProject9(bool useNewParser)
+        public void EmitToolsVersionAttributeToInMemoryProject9()
         {
             if (FrameworkLocationHelper.PathToDotNetFrameworkV35 == null)
             {
@@ -355,7 +343,7 @@ public void EmitToolsVersionAttributeToInMemoryProject9(bool useNewParser)
             }
 
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -365,9 +353,9 @@ public void EmitToolsVersionAttributeToInMemoryProject9(bool useNewParser)
                         Other|Win32 = Other|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, "3.5", _buildEventContext, CreateMockLoggingService());
 
@@ -378,12 +366,10 @@ public void EmitToolsVersionAttributeToInMemoryProject9(bool useNewParser)
         /// Test to make sure we properly set the ToolsVersion attribute on the in-memory project based
         /// on the Solution File Format Version.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void EmitToolsVersionAttributeToInMemoryProject10(bool useNewParser)
+        public void EmitToolsVersionAttributeToInMemoryProject10()
         {
             if (FrameworkLocationHelper.PathToDotNetFrameworkV35 == null)
             {
@@ -392,7 +378,7 @@ public void EmitToolsVersionAttributeToInMemoryProject10(bool useNewParser)
             }
 
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 10.00
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -402,9 +388,9 @@ public void EmitToolsVersionAttributeToInMemoryProject10(bool useNewParser)
                         Other|Win32 = Other|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, "3.5", _buildEventContext, CreateMockLoggingService());
 
@@ -421,7 +407,7 @@ public void DefaultSubToolsetIfSolutionVersionSubToolsetDoesntExist()
             Environment.SetEnvironmentVariable("VisualStudioVersion", null);
 
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 10.00
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -431,9 +417,9 @@ public void DefaultSubToolsetIfSolutionVersionSubToolsetDoesntExist()
                         Other|Win32 = Other|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = SolutionFile_OldParser_Tests.ParseSolutionHelper(solutionFileContents);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, null, _buildEventContext, CreateMockLoggingService());
 
@@ -457,15 +443,13 @@ public void DefaultSubToolsetIfSolutionVersionSubToolsetDoesntExist()
         /// Test to make sure that if the solution version corresponds to an existing sub-toolset version,
         /// barring other factors that might override, the sub-toolset will be based on the solution version.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void SubToolsetSetBySolutionVersion(bool useNewParser)
+        [Fact]
+        public void SubToolsetSetBySolutionVersion()
         {
             Environment.SetEnvironmentVariable("VisualStudioVersion", null);
 
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 12.00
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -475,9 +459,9 @@ public void SubToolsetSetBySolutionVersion(bool useNewParser)
                         Other|Win32 = Other|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, null, _buildEventContext, CreateMockLoggingService());
 
@@ -494,15 +478,13 @@ public void SubToolsetSetBySolutionVersion(bool useNewParser)
         /// <summary>
         /// Test to make sure that even if the solution version corresponds to an existing sub-toolset version,
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void SolutionBasedSubToolsetVersionOverriddenByEnvironment(bool useNewParser)
+        [Fact]
+        public void SolutionBasedSubToolsetVersionOverriddenByEnvironment()
         {
             Environment.SetEnvironmentVariable("VisualStudioVersion", "ABC");
 
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 12.00
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -512,9 +494,9 @@ public void SolutionBasedSubToolsetVersionOverriddenByEnvironment(bool useNewPar
                         Other|Win32 = Other|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, null, _buildEventContext, CreateMockLoggingService());
 
@@ -737,45 +719,44 @@ public void SolutionDoesntPassSubToolsetToChildProjects()
         /// Verify that we throw the appropriate error if the solution declares a dependency
         /// on a project that doesn't exist.
         /// </summary>
-        /// <remarks>This test would only work for the old parser. In the new parser the dependency is not added if it was not in the solution file.</remarks>
         [Fact]
         public void SolutionWithMissingDependencies()
         {
             Assert.Throws<InvalidProjectFileException>(() =>
             {
                 string solutionFileContents =
-                    """
-                    Microsoft Visual Studio Solution File, Format Version 12.00
-                    # Visual Studio 11
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "B", "Project2\B.csproj", "{881C1674-4ECA-451D-85B6-D7C59B7F16FA}"
-                        ProjectSection(ProjectDependencies) = postProject
-                            {4A727FF8-65F2-401E-95AD-7C8BBFBE3167} = {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}
-                        EndProjectSection
-                    EndProject
-                    Global
-                        GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                            Debug|Any CPU = Debug|Any CPU
-                            Debug|x64 = Debug|x64
-                            Release|Any CPU = Release|Any CPU
-                            Release|x64 = Release|x64
-                        EndGlobalSection
-                        GlobalSection(ProjectConfigurationPlatforms) = preSolution
-                            {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                            {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                            {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|x64.ActiveCfg = Debug|Any CPU
-                            {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|x64.Build.0 = Debug|Any CPU
-                            {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                            {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|Any CPU.Build.0 = Release|Any CPU
-                            {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|x64.ActiveCfg = Release|Any CPU
-                            {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|x64.Build.0 = Release|Any CPU
-                        EndGlobalSection
-                        GlobalSection(SolutionProperties) = preSolution
-                            HideSolutionNode = FALSE
-                        EndGlobalSection
-                    EndGlobal
-                    """;
+                    @"
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 11
+Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `B`, `Project2\B.csproj`, `{881C1674-4ECA-451D-85B6-D7C59B7F16FA}`
+    ProjectSection(ProjectDependencies) = postProject
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167} = {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}
+    EndProjectSection
+EndProject
+Global
+    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+        Debug|Any CPU = Debug|Any CPU
+        Debug|x64 = Debug|x64
+        Release|Any CPU = Release|Any CPU
+        Release|x64 = Release|x64
+    EndGlobalSection
+    GlobalSection(ProjectConfigurationPlatforms) = preSolution
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|x64.ActiveCfg = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|x64.Build.0 = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|Any CPU.ActiveCfg = Release|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|Any CPU.Build.0 = Release|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|x64.ActiveCfg = Release|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|x64.Build.0 = Release|Any CPU
+    EndGlobalSection
+    GlobalSection(SolutionProperties) = preSolution
+        HideSolutionNode = FALSE
+    EndGlobalSection
+EndGlobal
+".Replace("`", "\"");
 
-                SolutionFile sp = SolutionFile_OldParser_Tests.ParseSolutionHelper(solutionFileContents);
+                SolutionFile sp = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
                 ProjectInstance[] instances = SolutionProjectGenerator.Generate(sp, null, null, _buildEventContext, CreateMockLoggingService());
             });
         }
@@ -783,64 +764,62 @@ public void SolutionWithMissingDependencies()
         /// Blob should contain dependency info
         /// Here B depends on C
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void SolutionConfigurationWithDependencies(bool useNewParser)
+        [Fact]
+        public void SolutionConfigurationWithDependencies()
         {
             string solutionFileContents =
-                """
-                Microsoft Visual Studio Solution File, Format Version 12.00
-                # Visual Studio 11
-                Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "A", "Project1\A.csproj", "{786E302A-96CE-43DC-B640-D6B6CC9BF6C0}"
-                EndProject
-                Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "B", "Project2\B.csproj", "{881C1674-4ECA-451D-85B6-D7C59B7F16FA}"
-                    ProjectSection(ProjectDependencies) = postProject
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167} = {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}
-                    EndProjectSection
-                EndProject
-                Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "C", "Project3\C.csproj", "{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}"
-                EndProject
-                Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|Any CPU = Debug|Any CPU
-                        Debug|x64 = Debug|x64
-                        Release|Any CPU = Release|Any CPU
-                        Release|x64 = Release|x64
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = preSolution
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|x64.ActiveCfg = Debug|Any CPU
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|x64.Build.0 = Debug|Any CPU
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Release|Any CPU.Build.0 = Release|Any CPU
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Release|x64.ActiveCfg = Release|Any CPU
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Release|x64.Build.0 = Release|Any CPU
-                        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Debug|x64.ActiveCfg = Debug|Any CPU
-                        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Debug|x64.Build.0 = Debug|Any CPU
-                        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Release|Any CPU.Build.0 = Release|Any CPU
-                        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Release|x64.ActiveCfg = Release|Any CPU
-                        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Release|x64.Build.0 = Release|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|x64.ActiveCfg = Debug|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|x64.Build.0 = Debug|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|Any CPU.Build.0 = Release|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|x64.ActiveCfg = Release|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|x64.Build.0 = Release|Any CPU
-                    EndGlobalSection
-                    GlobalSection(SolutionProperties) = preSolution
-                        HideSolutionNode = FALSE
-                    EndGlobalSection
-                EndGlobal
-                """;
+                @"
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 11
+Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `A`, `Project1\A.csproj`, `{786E302A-96CE-43DC-B640-D6B6CC9BF6C0}`
+EndProject
+Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `B`, `Project2\B.csproj`, `{881C1674-4ECA-451D-85B6-D7C59B7F16FA}`
+    ProjectSection(ProjectDependencies) = postProject
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167} = {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}
+    EndProjectSection
+EndProject
+Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `C`, `Project3\C.csproj`, `{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}`
+EndProject
+Global
+    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+        Debug|Any CPU = Debug|Any CPU
+        Debug|x64 = Debug|x64
+        Release|Any CPU = Release|Any CPU
+        Release|x64 = Release|x64
+    EndGlobalSection
+    GlobalSection(ProjectConfigurationPlatforms) = preSolution
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|Any CPU.Build.0 = Debug|Any CPU
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|x64.ActiveCfg = Debug|Any CPU
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|x64.Build.0 = Debug|Any CPU
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Release|Any CPU.ActiveCfg = Release|Any CPU
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Release|Any CPU.Build.0 = Release|Any CPU
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Release|x64.ActiveCfg = Release|Any CPU
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Release|x64.Build.0 = Release|Any CPU
+        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Debug|Any CPU.Build.0 = Debug|Any CPU
+        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Debug|x64.ActiveCfg = Debug|Any CPU
+        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Debug|x64.Build.0 = Debug|Any CPU
+        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Release|Any CPU.ActiveCfg = Release|Any CPU
+        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Release|Any CPU.Build.0 = Release|Any CPU
+        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Release|x64.ActiveCfg = Release|Any CPU
+        {786E302A-96CE-43DC-B640-D6B6CC9BF6C0}.Release|x64.Build.0 = Release|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|x64.ActiveCfg = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|x64.Build.0 = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|Any CPU.ActiveCfg = Release|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|Any CPU.Build.0 = Release|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|x64.ActiveCfg = Release|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Release|x64.Build.0 = Release|Any CPU
+    EndGlobalSection
+    GlobalSection(SolutionProperties) = preSolution
+        HideSolutionNode = FALSE
+    EndGlobalSection
+EndGlobal
+".Replace("`", "\"");
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectRootElement projectXml = ProjectRootElement.Create();
 
@@ -859,14 +838,11 @@ public void SolutionConfigurationWithDependencies(bool useNewParser)
             string solutionConfigurationContents = msbuildProject.GetPropertyValue("CurrentSolutionConfigurationContents");
 
             // Only the specified solution configuration is represented in THE BLOB: nothing for x64 in this case
-            string expected =
-                $$"""
-                <SolutionConfiguration>
-                  <ProjectConfiguration Project="{786E302A-96CE-43DC-B640-D6B6CC9BF6C0}" AbsolutePath="##temp##{{Path.Combine("Project1", "A.csproj")}}" BuildProjectInSolution="True">Debug|AnyCPU</ProjectConfiguration>
-                  <ProjectConfiguration Project="{881C1674-4ECA-451D-85B6-D7C59B7F16FA}" AbsolutePath="##temp##{{Path.Combine("Project2", "B.csproj")}}" BuildProjectInSolution="True">Debug|AnyCPU<ProjectDependency Project="{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}" /></ProjectConfiguration>
-                  <ProjectConfiguration Project="{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}" AbsolutePath="##temp##{{Path.Combine("Project3", "C.csproj")}}" BuildProjectInSolution="True">Debug|AnyCPU</ProjectConfiguration>
-                </SolutionConfiguration>
-                """.Replace("##temp##", FileUtilities.TempFileDirectory);
+            string expected = $@"<SolutionConfiguration>
+  <ProjectConfiguration Project=`{{786E302A-96CE-43DC-B640-D6B6CC9BF6C0}}` AbsolutePath=`##temp##{Path.Combine("Project1", "A.csproj")}` BuildProjectInSolution=`True`>Debug|AnyCPU</ProjectConfiguration>
+  <ProjectConfiguration Project=`{{881C1674-4ECA-451D-85B6-D7C59B7F16FA}}` AbsolutePath=`##temp##{Path.Combine("Project2", "B.csproj")}` BuildProjectInSolution=`True`>Debug|AnyCPU<ProjectDependency Project=`{{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}}` /></ProjectConfiguration>
+  <ProjectConfiguration Project=`{{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}}` AbsolutePath=`##temp##{Path.Combine("Project3", "C.csproj")}` BuildProjectInSolution=`True`>Debug|AnyCPU</ProjectConfiguration>
+</SolutionConfiguration>".Replace("`", "\"").Replace("##temp##", FileUtilities.TempFileDirectory);
 
             Helpers.VerifyAssertLineByLine(expected, solutionConfigurationContents);
         }
@@ -884,19 +860,19 @@ public void SolutionGeneratingMetaproj()
                 TransientTestFile proj2 = env.CreateFile("B.csproj", @"<Project><Target Name=""Printer""><Message Importance=""high"" Text=""print string"" /></Target></Project>");
                 TransientTestFile proj3 = env.CreateFile("C.csproj", @"<Project><Target Name=""Printer""><Message Importance=""high"" Text=""print string"" /></Target></Project>");
                 TransientTestFile proj = env.CreateFile("mysln.sln",
-                    $$"""
-                    Microsoft Visual Studio Solution File, Format Version 12.00
-                    # Visual Studio 11
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "A", "{{proj1.Path}}", "{786E302A-96CE-43DC-B640-D6B6CC9BF6C0}"
-                    EndProject
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "B", "{{proj2.Path}}", "{881C1674-4ECA-451D-85B6-D7C59B7F16FA}"
-                        ProjectSection(ProjectDependencies) = postProject
-                            {"{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}"} = {"{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}"}
-                        EndProjectSection
-                    EndProject
-                    Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "C", "{{proj3.Path}}", "{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}"
-                    EndProject
-                    """);
+                @$"
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 11
+Project(`{"{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"}`) = `A`, `{proj1.Path}`, `{"{786E302A-96CE-43DC-B640-D6B6CC9BF6C0}"}`
+EndProject
+Project(`{"{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"}`) = `B`, `{proj2.Path}`, `{"{881C1674-4ECA-451D-85B6-D7C59B7F16FA}"}`
+    ProjectSection(ProjectDependencies) = postProject
+        {"{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}"} = {"{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}"}
+    EndProjectSection
+EndProject
+Project(`{"{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"}`) = `C`, `{proj3.Path}`, `{"{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}"}`
+EndProject
+".Replace("`", "\""));
                 RunnerUtilities.ExecMSBuild("\"" + proj.Path + "\"", out bool successfulExit);
                 successfulExit.ShouldBeTrue();
             }
@@ -914,37 +890,37 @@ public void SolutionConfigurationWithDependenciesRelaysItsOutputs()
         {
             #region Large strings representing solution & projects
             const string solutionFileContents =
-                """
-                Microsoft Visual Studio Solution File, Format Version 12.00
-                # Visual Studio 11
-                Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `B`, `B.csproj`, `{881C1674-4ECA-451D-85B6-D7C59B7F16FA}`
-                    ProjectSection(ProjectDependencies) = postProject
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167} = {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}
-                    EndProjectSection
-                EndProject
-                Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `C`, `C.csproj`, `{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}`
-                EndProject
-                Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `D`, `D.csproj`, `{B6E7E06F-FC0B-48F1-911A-55E0E1566F00}`
-                EndProject
-                Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|Any CPU = Debug|Any CPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = preSolution
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {B6E7E06F-FC0B-48F1-911A-55E0E1566F00}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {B6E7E06F-FC0B-48F1-911A-55E0E1566F00}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                    EndGlobalSection
-                    GlobalSection(SolutionProperties) = preSolution
-                        HideSolutionNode = FALSE
-                    EndGlobalSection
-                EndGlobal
-                """;
+                @"
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 11
+Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `B`, `B.csproj`, `{881C1674-4ECA-451D-85B6-D7C59B7F16FA}`
+    ProjectSection(ProjectDependencies) = postProject
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167} = {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}
+    EndProjectSection
+EndProject
+Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `C`, `C.csproj`, `{4A727FF8-65F2-401E-95AD-7C8BBFBE3167}`
+EndProject
+Project(`{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}`) = `D`, `D.csproj`, `{B6E7E06F-FC0B-48F1-911A-55E0E1566F00}`
+EndProject
+Global
+    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+        Debug|Any CPU = Debug|Any CPU
+    EndGlobalSection
+    GlobalSection(ProjectConfigurationPlatforms) = preSolution
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {4A727FF8-65F2-401E-95AD-7C8BBFBE3167}.Debug|Any CPU.Build.0 = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {881C1674-4ECA-451D-85B6-D7C59B7F16FA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+        {B6E7E06F-FC0B-48F1-911A-55E0E1566F00}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {B6E7E06F-FC0B-48F1-911A-55E0E1566F00}.Debug|Any CPU.Build.0 = Debug|Any CPU
+    EndGlobalSection
+    GlobalSection(SolutionProperties) = preSolution
+        HideSolutionNode = FALSE
+    EndGlobalSection
+EndGlobal
+";
             const string projectBravoFileContents =
-                    """
+                    @"
                         <Project ToolsVersion='msbuilddefaulttoolsversion' DefaultTargets='Build' xmlns='msbuildnamespace'>
                             <Target Name='Build' Outputs='@(ComputedQuestion)'>
                                 <ItemGroup>
@@ -958,9 +934,9 @@ public void SolutionConfigurationWithDependenciesRelaysItsOutputs()
                                 </ProjectReference>
                             </ItemGroup>
                         </Project>
-                    """;
+                    ";
             const string projectCharlieFileContents =
-                    """
+                    @"
                         <Project ToolsVersion='msbuilddefaulttoolsversion' DefaultTargets='Build' xmlns='msbuildnamespace'>
                             <Target Name='Build' Outputs='@(ComputedAnswer)'>
                                 <ItemGroup>
@@ -968,9 +944,9 @@ public void SolutionConfigurationWithDependenciesRelaysItsOutputs()
                                 </ItemGroup>
                             </Target>
                         </Project>
-                    """;
+                    ";
             const string projectDeltaFileContents =
-                    """
+                    @"
                         <Project ToolsVersion='msbuilddefaulttoolsversion' DefaultTargets='Build' xmlns='msbuildnamespace'>
                             <PropertyGroup>
                                 <ProjectGuid>{B6E7E06F-FC0B-48F1-911A-55E0E1566F00}</ProjectGuid>
@@ -981,62 +957,60 @@ public void SolutionConfigurationWithDependenciesRelaysItsOutputs()
                                 </ItemGroup>
                             </Target>
                         </Project>
-                    """;
-            const string automaticProjectFileContents =
-                """
-                <Project ToolsVersion='msbuilddefaulttoolsversion' DefaultTargets='compile' xmlns='msbuildnamespace'>
-                    <Target Name='compile'>
-                        <!-- Build projects to get a baseline for their output -->
-                        <MSBuild Projects='B.csproj' Targets='Build'>
-                            <Output
-                                TaskParameter='TargetOutputs'
-                                ItemName='BravoProjectOutputs' />
-                        </MSBuild>
-                        <Message Importance='high' Text='BravoProjectOutputs: @(BravoProjectOutputs)' />
-
-                        <MSBuild Projects='C.csproj' Targets='Build'>
-                            <Output
-                                TaskParameter='TargetOutputs'
-                                ItemName='CharlieProjectOutputs' />
-                        </MSBuild>
-                        <Message Importance='high' Text='CharlieProjectOutputs: @(CharlieProjectOutputs)' />
-
-                        <MSBuild Projects='D.csproj' Targets='Build'>
-                            <Output
-                                TaskParameter='TargetOutputs'
-                                ItemName='DeltaProjectOutputs' />
-                        </MSBuild>
-                        <Message Importance='high' Text='DeltaProjectOutputs: @(DeltaProjectOutputs)' />
-
-                        <PropertyGroup>
-                            <StringifiedBravoProjectOutputs>@(BravoProjectOutputs)</StringifiedBravoProjectOutputs>
-                            <StringifiedCharlieProjectOutputs>@(CharlieProjectOutputs)</StringifiedCharlieProjectOutputs>
-                            <StringifiedDeltaProjectOutputs>@(DeltaProjectOutputs)</StringifiedDeltaProjectOutputs>
-                        </PropertyGroup>
-
-                        <!-- Explicitly build the metaproject generated for B -->
-                        <MSBuild Projects='B.csproj.metaproj' Targets='Build'>
-                            <Output
-                                TaskParameter='TargetOutputs'
-                                ItemName='BravoMetaProjectOutputs' />
-                        </MSBuild>
-                        <Message Importance='high' Text='BravoMetaProjectOutputs: @(BravoMetaProjectOutputs)' />
-                        <Error Condition=` '@(BravoProjectOutputs)' != '@(BravoMetaProjectOutputs)' ` Text='Metaproj outputs must match outputs of normal project build.' />
-
-                        <!-- Build the solution as a whole (which will build the metaproj and return overall outputs) -->
-                        <MSBuild Projects='MSBuildIssue.sln'>
-                            <Output
-                                TaskParameter='TargetOutputs'
-                                ItemName='SolutionProjectOutputs' />
-                        </MSBuild>
-                        <Message Importance='high' Text='SolutionProjectOutputs: @(SolutionProjectOutputs)' />
-                        <Error Condition=` '@(SolutionProjectOutputs->Count())' != '3' ` Text='Overall sln outputs must include outputs of each referenced project (there should be 3).' />
-                        <Error Condition=` '@(SolutionProjectOutputs->AnyHaveMetadataValue('Identity', '$(StringifiedBravoProjectOutputs)'))' != 'true'` Text='Overall sln outputs must include outputs of normal project build of project B.' />
-                        <Error Condition=` '@(SolutionProjectOutputs->AnyHaveMetadataValue('Identity', '$(StringifiedCharlieProjectOutputs)'))' != 'true' ` Text='Overall sln outputs must include outputs of normal project build of project C.' />
-                        <Error Condition=` '@(SolutionProjectOutputs->AnyHaveMetadataValue('Identity', '$(StringifiedDeltaProjectOutputs)'))' != 'true' ` Text='Overall sln outputs must include outputs of normal project build of project D.' />
-                    </Target>
-                </Project>
-                """;
+                    ";
+            const string automaticProjectFileContents = @"
+<Project ToolsVersion='msbuilddefaulttoolsversion' DefaultTargets='compile' xmlns='msbuildnamespace'>
+    <Target Name='compile'>
+        <!-- Build projects to get a baseline for their output -->
+        <MSBuild Projects='B.csproj' Targets='Build'>
+            <Output
+                TaskParameter='TargetOutputs'
+                ItemName='BravoProjectOutputs' />
+        </MSBuild>
+        <Message Importance='high' Text='BravoProjectOutputs: @(BravoProjectOutputs)' />
+
+        <MSBuild Projects='C.csproj' Targets='Build'>
+            <Output
+                TaskParameter='TargetOutputs'
+                ItemName='CharlieProjectOutputs' />
+        </MSBuild>
+        <Message Importance='high' Text='CharlieProjectOutputs: @(CharlieProjectOutputs)' />
+
+        <MSBuild Projects='D.csproj' Targets='Build'>
+            <Output
+                TaskParameter='TargetOutputs'
+                ItemName='DeltaProjectOutputs' />
+        </MSBuild>
+        <Message Importance='high' Text='DeltaProjectOutputs: @(DeltaProjectOutputs)' />
+
+        <PropertyGroup>
+            <StringifiedBravoProjectOutputs>@(BravoProjectOutputs)</StringifiedBravoProjectOutputs>
+            <StringifiedCharlieProjectOutputs>@(CharlieProjectOutputs)</StringifiedCharlieProjectOutputs>
+            <StringifiedDeltaProjectOutputs>@(DeltaProjectOutputs)</StringifiedDeltaProjectOutputs>
+        </PropertyGroup>
+
+        <!-- Explicitly build the metaproject generated for B -->
+        <MSBuild Projects='B.csproj.metaproj' Targets='Build'>
+            <Output
+                TaskParameter='TargetOutputs'
+                ItemName='BravoMetaProjectOutputs' />
+        </MSBuild>
+        <Message Importance='high' Text='BravoMetaProjectOutputs: @(BravoMetaProjectOutputs)' />
+        <Error Condition=` '@(BravoProjectOutputs)' != '@(BravoMetaProjectOutputs)' ` Text='Metaproj outputs must match outputs of normal project build.' />
+
+        <!-- Build the solution as a whole (which will build the metaproj and return overall outputs) -->
+        <MSBuild Projects='MSBuildIssue.sln'>
+            <Output
+                TaskParameter='TargetOutputs'
+                ItemName='SolutionProjectOutputs' />
+        </MSBuild>
+        <Message Importance='high' Text='SolutionProjectOutputs: @(SolutionProjectOutputs)' />
+        <Error Condition=` '@(SolutionProjectOutputs->Count())' != '3' ` Text='Overall sln outputs must include outputs of each referenced project (there should be 3).' />
+        <Error Condition=` '@(SolutionProjectOutputs->AnyHaveMetadataValue('Identity', '$(StringifiedBravoProjectOutputs)'))' != 'true'` Text='Overall sln outputs must include outputs of normal project build of project B.' />
+        <Error Condition=` '@(SolutionProjectOutputs->AnyHaveMetadataValue('Identity', '$(StringifiedCharlieProjectOutputs)'))' != 'true' ` Text='Overall sln outputs must include outputs of normal project build of project C.' />
+        <Error Condition=` '@(SolutionProjectOutputs->AnyHaveMetadataValue('Identity', '$(StringifiedDeltaProjectOutputs)'))' != 'true' ` Text='Overall sln outputs must include outputs of normal project build of project D.' />
+    </Target>
+</Project>";
             #endregion
 
             var logger = new MockLogger(output);
@@ -1065,13 +1039,11 @@ public void SolutionConfigurationWithDependenciesRelaysItsOutputs()
         /// <summary>
         /// Test the SolutionProjectGenerator.AddPropertyGroupForSolutionConfiguration method
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void TestAddPropertyGroupForSolutionConfiguration(bool useNewParser)
+        [Fact]
+        public void TestAddPropertyGroupForSolutionConfiguration()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
@@ -1091,9 +1063,9 @@ public void TestAddPropertyGroupForSolutionConfiguration(bool useNewParser)
                         {A6F99D27-47B9-4EA4-BFC9-25157CBDC281}.Debug|Mixed Platforms.Build.0 = VCConfig1|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectRootElement projectXml = ProjectRootElement.Create();
 
@@ -1140,13 +1112,11 @@ public void TestAddPropertyGroupForSolutionConfiguration(bool useNewParser)
         /// <summary>
         /// Make sure that BuildProjectInSolution is set to true of the Build.0 entry is in the solution configuration.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void TestAddPropertyGroupForSolutionConfigurationBuildProjectInSolutionSet(bool useNewParser)
+        [Fact]
+        public void TestAddPropertyGroupForSolutionConfigurationBuildProjectInSolutionSet()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
@@ -1161,9 +1131,9 @@ public void TestAddPropertyGroupForSolutionConfigurationBuildProjectInSolutionSe
                         {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Mixed Platforms.Build.0 = CSConfig1|Any CPU
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectRootElement projectXml = ProjectRootElement.Create();
 
@@ -1186,13 +1156,11 @@ public void TestAddPropertyGroupForSolutionConfigurationBuildProjectInSolutionSe
         /// <summary>
         /// Make sure that BuildProjectInSolution is set to false of the Build.0 entry is in the solution configuration.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void TestAddPropertyGroupForSolutionConfigurationBuildProjectInSolutionNotSet(bool useNewParser)
+        [Fact]
+        public void TestAddPropertyGroupForSolutionConfigurationBuildProjectInSolutionNotSet()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
@@ -1206,9 +1174,9 @@ public void TestAddPropertyGroupForSolutionConfigurationBuildProjectInSolutionNo
                         {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Mixed Platforms.ActiveCfg = CSConfig1|Any CPU
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectRootElement projectXml = ProjectRootElement.Create();
 
@@ -1232,12 +1200,10 @@ public void TestAddPropertyGroupForSolutionConfigurationBuildProjectInSolutionNo
         /// In this bug, SkipNonexistentProjects was always set to 'Build'. It should be 'Build' for metaprojects and 'True' for everything else.
         /// The repro below has one of each case. WebProjects can't build so they are set as SkipNonexistentProjects='Build'
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void Regress751742_SkipNonexistentProjects(bool useNewParser)
+        public void Regress751742_SkipNonexistentProjects()
         {
             if (FrameworkLocationHelper.PathToDotNetFrameworkV20 == null)
             {
@@ -1246,7 +1212,7 @@ public void Regress751742_SkipNonexistentProjects(bool useNewParser)
             }
 
             var solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
@@ -1266,10 +1232,10 @@ public void Regress751742_SkipNonexistentProjects(bool useNewParser)
                         {A6F99D27-47B9-4EA4-BFC9-25157CBDC281}.Debug|Mixed Platforms.Build.0 = VCConfig1|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
             // We're not passing in a /tv:xx switch, so the solution project will have tools version 2.0
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            var solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             var instance = SolutionProjectGenerator.Generate(solution, null, ObjectModelHelpers.MSBuildDefaultToolsVersion, _buildEventContext, CreateMockLoggingService())[0];
 
@@ -1308,13 +1274,11 @@ public void Regress751742_SkipNonexistentProjects(bool useNewParser)
         /// if set when building a solution, will be specified as the ToolsVersion on the MSBuild task when
         /// building the projects contained within the solution.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void ToolsVersionOverrideShouldBeSpecifiedOnMSBuildTaskInvocations(bool useNewParser)
+        [Fact]
+        public void ToolsVersionOverrideShouldBeSpecifiedOnMSBuildTaskInvocations()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
@@ -1334,10 +1298,10 @@ public void ToolsVersionOverrideShouldBeSpecifiedOnMSBuildTaskInvocations(bool u
                         {A6F99D27-47B9-4EA4-BFC9-25157CBDC281}.Debug|Mixed Platforms.Build.0 = VCConfig1|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
             // We're not passing in a /tv:xx switch, so the solution project will have tools version 2.0
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, ObjectModelHelpers.MSBuildDefaultToolsVersion, _buildEventContext, CreateMockLoggingService());
 
@@ -1376,44 +1340,42 @@ public void ToolsVersionOverrideShouldBeSpecifiedOnMSBuildTaskInvocations(bool u
         /// <summary>
         /// Make sure that whatever the solution ToolsVersion is, it gets mapped to all its metaprojs, too.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void SolutionWithDependenciesHasCorrectToolsVersionInMetaprojs(bool useNewParser)
+        [Fact]
+        public void SolutionWithDependenciesHasCorrectToolsVersionInMetaprojs()
         {
             string solutionFileContents =
-                """
-                Microsoft Visual Studio Solution File, Format Version 12.00
-                Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ConsoleApplication2', 'ConsoleApplication2\ConsoleApplication2.csproj', '{5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}'
-                    ProjectSection(ProjectDependencies) = postProject
-                        {E0D295A1-CAFA-4E68-9929-468657DAAC6C} = {E0D295A1-CAFA-4E68-9929-468657DAAC6C}
-                    EndProjectSection
-                EndProject
-                Project('{F184B08F-C81C-45F6-A57F-5ABD9991F28F}') = 'ConsoleApplication1', 'ConsoleApplication1\ConsoleApplication1.vbproj', '{E0D295A1-CAFA-4E68-9929-468657DAAC6C}'
-                EndProject
-                Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|Any CPU = Debug|Any CPU
-                        Release|Any CPU = Release|Any CPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                        {5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}.Release|Any CPU.Build.0 = Release|Any CPU
-                        {E0D295A1-CAFA-4E68-9929-468657DAAC6C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {E0D295A1-CAFA-4E68-9929-468657DAAC6C}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {E0D295A1-CAFA-4E68-9929-468657DAAC6C}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {E0D295A1-CAFA-4E68-9929-468657DAAC6C}.Release|Any CPU.Build.0 = Release|Any CPU
-                    EndGlobalSection
-                    GlobalSection(SolutionProperties) = preSolution
-                        HideSolutionNode = FALSE
-                    EndGlobalSection
-                EndGlobal
-                """;
+                @"
+Microsoft Visual Studio Solution File, Format Version 12.00
+Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ConsoleApplication2', 'ConsoleApplication2\ConsoleApplication2.csproj', '{5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}'
+    ProjectSection(ProjectDependencies) = postProject
+        {E0D295A1-CAFA-4E68-9929-468657DAAC6C} = {E0D295A1-CAFA-4E68-9929-468657DAAC6C}
+    EndProjectSection
+EndProject
+Project('{F184B08F-C81C-45F6-A57F-5ABD9991F28F}') = 'ConsoleApplication1', 'ConsoleApplication1\ConsoleApplication1.vbproj', '{E0D295A1-CAFA-4E68-9929-468657DAAC6C}'
+EndProject
+Global
+    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+        Debug|Any CPU = Debug|Any CPU
+        Release|Any CPU = Release|Any CPU
+    EndGlobalSection
+    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+        {5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+        {5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+        {5B97A3C7-3DEE-47A4-870F-5CB6384FE6A4}.Release|Any CPU.Build.0 = Release|Any CPU
+        {E0D295A1-CAFA-4E68-9929-468657DAAC6C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {E0D295A1-CAFA-4E68-9929-468657DAAC6C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+        {E0D295A1-CAFA-4E68-9929-468657DAAC6C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+        {E0D295A1-CAFA-4E68-9929-468657DAAC6C}.Release|Any CPU.Build.0 = Release|Any CPU
+    EndGlobalSection
+    GlobalSection(SolutionProperties) = preSolution
+        HideSolutionNode = FALSE
+    EndGlobalSection
+EndGlobal
+                ";
 
             // We're not passing in a /tv:xx switch, so the solution project will have tools version 2.0
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             string[] solutionToolsVersions = { "4.0", ObjectModelHelpers.MSBuildDefaultToolsVersion };
 
@@ -1447,13 +1409,11 @@ public void SolutionWithDependenciesHasCorrectToolsVersionInMetaprojs(bool useNe
         /// <summary>
         /// Test the SolutionProjectGenerator.Generate method has its toolset redirected correctly.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void ToolsVersionOverrideCausesToolsetRedirect(bool useNewParser)
+        [Fact]
+        public void ToolsVersionOverrideCausesToolsetRedirect()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'ClassLibrary1', 'ClassLibrary1\ClassLibrary1.csproj', '{6185CC21-BE89-448A-B3C0-D1C27112E595}'
@@ -1473,8 +1433,8 @@ public void ToolsVersionOverrideCausesToolsetRedirect(bool useNewParser)
                         {A6F99D27-47B9-4EA4-BFC9-25157CBDC281}.Debug|Mixed Platforms.Build.0 = VCConfig1|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+                ";
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
             bool caughtException = false;
 
             try
@@ -1494,13 +1454,11 @@ public void ToolsVersionOverrideCausesToolsetRedirect(bool useNewParser)
         /// <summary>
         /// Test the SolutionProjectGenerator.AddPropertyGroupForSolutionConfiguration method
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void TestDisambiguateProjectTargetName(bool useNewParser)
+        [Fact]
+        public void TestDisambiguateProjectTargetName()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}') = 'Build', 'Build\Build.csproj', '{21397922-C38F-4A0E-B950-77B3FBD51881}'
@@ -1520,9 +1478,9 @@ public void TestDisambiguateProjectTargetName(bool useNewParser)
                                 HideSolutionNode = FALSE
                         EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, null, BuildEventContext.Invalid, CreateMockLoggingService());
 
@@ -1576,13 +1534,11 @@ public void TestDisambiguateProjectTargetName(bool useNewParser)
         /// <summary>
         /// Tests the algorithm for choosing default configuration/platform values for solutions
         /// </summary>
-        /// <remarks>This test would only work for the old parser. In the new parser SolutionConfigurations are not available,
-        /// and constructed from projects configurations.</remarks>
         [Fact]
         public void TestConfigurationPlatformDefaults1()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -1594,9 +1550,9 @@ public void TestConfigurationPlatformDefaults1()
                         Release|Win32 = Release|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = SolutionFile_OldParser_Tests.ParseSolutionHelper(solutionFileContents);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             // These used to exist on the engine, but now need to be passed in explicitly
             IDictionary<string, string> globalProperties = new Dictionary<string, string>();
@@ -1616,13 +1572,11 @@ public void TestConfigurationPlatformDefaults1()
         /// <summary>
         /// Tests the algorithm for choosing default configuration/platform values for solutions
         /// </summary>
-        /// <remarks>This test would only work for the old parser. In the new parser SolutionConfigurations are not available,
-        /// and constructed from projects configurations.</remarks>
         [Fact]
         public void TestConfigurationPlatformDefaults2()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -1632,9 +1586,9 @@ public void TestConfigurationPlatformDefaults2()
                         Other|Win32 = Other|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = SolutionFile_OldParser_Tests.ParseSolutionHelper(solutionFileContents);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, null, BuildEventContext.Invalid, CreateMockLoggingService());
 
@@ -1648,12 +1602,10 @@ public void TestConfigurationPlatformDefaults2()
         /// <summary>
         /// Tests the algorithm for choosing default Venus configuration values for solutions
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void TestVenusConfigurationDefaults(bool useNewParser)
+        public void TestVenusConfigurationDefaults()
         {
             if (FrameworkLocationHelper.PathToDotNetFrameworkV20 == null)
             {
@@ -1663,13 +1615,13 @@ public void TestVenusConfigurationDefaults(bool useNewParser)
 
             Dictionary<string, string> globalProperties = new Dictionary<string, string>();
             globalProperties["Configuration"] = "Debug";
-            ProjectInstance msbuildProject = CreateVenusSolutionProject(globalProperties, useNewParser);
+            ProjectInstance msbuildProject = CreateVenusSolutionProject(globalProperties);
 
             // ASP.NET configuration should match the selected solution configuration
             Assert.Equal("Debug", msbuildProject.GetPropertyValue("AspNetConfiguration"));
 
             globalProperties["Configuration"] = "Release";
-            msbuildProject = CreateVenusSolutionProject(globalProperties, useNewParser);
+            msbuildProject = CreateVenusSolutionProject(globalProperties);
             Assert.Equal("Release", msbuildProject.GetPropertyValue("AspNetConfiguration"));
 
             // Check that the two standard Asp.net configurations are represented on the targets
@@ -1680,12 +1632,10 @@ public void TestVenusConfigurationDefaults(bool useNewParser)
         /// <summary>
         /// Tests that the correct value for TargetFrameworkVersion gets set when creating Venus solutions
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void VenusSolutionDefaultTargetFrameworkVersion(bool useNewParser)
+        public void VenusSolutionDefaultTargetFrameworkVersion()
         {
             if (FrameworkLocationHelper.PathToDotNetFrameworkV20 == null)
             {
@@ -1694,7 +1644,7 @@ public void VenusSolutionDefaultTargetFrameworkVersion(bool useNewParser)
             }
 
             // v4.0 by default
-            ProjectInstance msbuildProject = CreateVenusSolutionProject(useNewParser);
+            ProjectInstance msbuildProject = CreateVenusSolutionProject();
             Assert.Equal("v4.0", msbuildProject.GetPropertyValue("TargetFrameworkVersion"));
 
             if (FrameworkLocationHelper.PathToDotNetFrameworkV35 == null)
@@ -1704,36 +1654,34 @@ public void VenusSolutionDefaultTargetFrameworkVersion(bool useNewParser)
             }
 
             // v3.5 if MSBuildToolsVersion is 3.5
-            msbuildProject = CreateVenusSolutionProject("3.5", useNewParser);
+            msbuildProject = CreateVenusSolutionProject("3.5");
             Assert.Equal("v3.5", msbuildProject.GetPropertyValue("TargetFrameworkVersion"));
 
             // v2.0 if MSBuildToolsVersion is 2.0
-            msbuildProject = CreateVenusSolutionProject("2.0", useNewParser);
+            msbuildProject = CreateVenusSolutionProject("2.0");
             Assert.Equal("v2.0", msbuildProject.GetPropertyValue("TargetFrameworkVersion"));
 
             // may be user defined
             IDictionary<string, string> globalProperties = new Dictionary<string, string>();
             globalProperties.Add("TargetFrameworkVersion", "userdefined");
-            msbuildProject = CreateVenusSolutionProject(globalProperties, useNewParser);
+            msbuildProject = CreateVenusSolutionProject(globalProperties);
             Assert.Equal("userdefined", msbuildProject.GetPropertyValue("TargetFrameworkVersion"));
         }
 
         /// <summary>
         /// Tests the algorithm for choosing target framework paths for ResolveAssemblyReferences for Venus
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void TestTargetFrameworkPaths0(bool useNewParser)
+        public void TestTargetFrameworkPaths0()
         {
             if (FrameworkLocationHelper.PathToDotNetFrameworkSdkV20 != null)
             {
                 IDictionary<string, string> globalProperties = new Dictionary<string, string>();
                 globalProperties.Add("TargetFrameworkVersion", "v2.0");
 
-                ProjectInstance msbuildProject = CreateVenusSolutionProject("2.0", useNewParser);
+                ProjectInstance msbuildProject = CreateVenusSolutionProject("2.0");
 
                 // ToolsVersion is 2.0, TargetFrameworkVersion is v2.0 --> one item pointing to v2.0
                 Assert.Equal("2.0", msbuildProject.ToolsVersion);
@@ -1748,12 +1696,10 @@ public void TestTargetFrameworkPaths0(bool useNewParser)
         /// <summary>
         /// Tests the algorithm for choosing target framework paths for ResolveAssemblyReferences for Venus
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void TestTargetFrameworkPaths1(bool useNewParser)
+        public void TestTargetFrameworkPaths1()
         {
             if (FrameworkLocationHelper.PathToDotNetFrameworkV20 == null)
             {
@@ -1761,7 +1707,7 @@ public void TestTargetFrameworkPaths1(bool useNewParser)
                 return;
             }
 
-            ProjectInstance msbuildProject = CreateVenusSolutionProject(useNewParser);
+            ProjectInstance msbuildProject = CreateVenusSolutionProject();
 
             // ToolsVersion is 4.0, TargetFrameworkVersion is v2.0 --> one item pointing to v2.0
             msbuildProject.SetProperty("TargetFrameworkVersion", "v2.0");
@@ -1776,12 +1722,10 @@ public void TestTargetFrameworkPaths1(bool useNewParser)
         /// <summary>
         /// Tests the algorithm for choosing target framework paths for ResolveAssemblyReferences for Venus
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void TestTargetFrameworkPaths2(bool useNewParser)
+        public void TestTargetFrameworkPaths2()
         {
             if (FrameworkLocationHelper.PathToDotNetFrameworkV20 == null)
             {
@@ -1789,7 +1733,7 @@ public void TestTargetFrameworkPaths2(bool useNewParser)
                 return;
             }
 
-            ProjectInstance msbuildProject = CreateVenusSolutionProject(useNewParser);
+            ProjectInstance msbuildProject = CreateVenusSolutionProject();
 
             // ToolsVersion is 4.0, TargetFrameworkVersion is v4.0 --> items for v2.0 and v4.0
             msbuildProject.SetProperty("TargetFrameworkVersion", "v4.0");
@@ -1827,13 +1771,11 @@ public void TestTargetFrameworkPaths2(bool useNewParser)
         /// <summary>
         /// Test the PredictActiveSolutionConfigurationName method
         /// </summary>
-        /// <remarks>This test would only work for the old parser.
-        /// In the new parser SolutionConfigurations are not available, and constructed from projects configurations.</remarks>
         [Fact]
         public void TestPredictSolutionConfigurationName()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -1843,9 +1785,9 @@ public void TestPredictSolutionConfigurationName()
                         Debug|Win32 = Debug|Win32
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = SolutionFile_OldParser_Tests.ParseSolutionHelper(solutionFileContents);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             IDictionary<string, string> globalProperties = new Dictionary<string, string>();
 
@@ -1864,13 +1806,11 @@ public void TestPredictSolutionConfigurationName()
         /// <summary>
         /// Verifies that the SolutionProjectGenerator will correctly escape project file paths
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void SolutionGeneratorEscapingProjectFilePaths(bool useNewParser)
+        [Fact]
+        public void SolutionGeneratorEscapingProjectFilePaths()
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{F184B08F-C81C-45F6-A57F-5ABD9991F28F}') = 'ConsoleApplication1', '%abtest\ConsoleApplication1.vbproj', '{AB3413A6-D689-486D-B7F0-A095371B3F13}'
@@ -1890,9 +1830,9 @@ public void SolutionGeneratorEscapingProjectFilePaths(bool useNewParser)
                         HideSolutionNode = FALSE
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             // Creating a ProjectRootElement shouldn't affect the ProjectCollection at all
             Assert.Empty(ProjectCollection.GlobalProjectCollection.LoadedProjects);
@@ -1909,10 +1849,8 @@ public void SolutionGeneratorEscapingProjectFilePaths(bool useNewParser)
         /// <summary>
         /// Verifies that the SolutionProjectGenerator will emit a solution file.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void SolutionGeneratorCanEmitSolutions(bool useNewParser)
+        [Fact]
+        public void SolutionGeneratorCanEmitSolutions()
         {
             string oldValueForMSBuildEmitSolution = Environment.GetEnvironmentVariable("MSBuildEmitSolution");
 
@@ -1920,7 +1858,7 @@ public void SolutionGeneratorCanEmitSolutions(bool useNewParser)
             ProjectCollection.GlobalProjectCollection.UnloadAllProjects();
 
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{F184B08F-C81C-45F6-A57F-5ABD9991F28F}') = 'ConsoleApplication1', 'ConsoleApplication1\ConsoleApplication1.vbproj', '{AB3413A6-D689-486D-B7F0-A095371B3F13}'
@@ -1940,7 +1878,7 @@ public void SolutionGeneratorCanEmitSolutions(bool useNewParser)
                         HideSolutionNode = FALSE
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
             SolutionFile solution = null;
             using ProjectCollection collection = new ProjectCollection();
@@ -1949,7 +1887,7 @@ public void SolutionGeneratorCanEmitSolutions(bool useNewParser)
             {
                 Environment.SetEnvironmentVariable("MSBuildEmitSolution", "1");
 
-                solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+                solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
                 // Creating a ProjectRootElement shouldn't affect the ProjectCollection at all
                 Assert.Empty(ProjectCollection.GlobalProjectCollection.LoadedProjects);
@@ -1981,18 +1919,16 @@ public void SolutionGeneratorCanEmitSolutions(bool useNewParser)
         /// Make sure that we output a warning and don't build anything when we're given an invalid
         /// solution configuration and SkipInvalidConfigurations is set to true.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
+        [Fact]
         [Trait("Category", "netcore-osx-failing")]
         [Trait("Category", "netcore-linux-failing")]
-        public void TestSkipInvalidConfigurationsCase(bool useNewParser)
+        public void TestSkipInvalidConfigurationsCase()
         {
             string tmpFileName = FileUtilities.GetTemporaryFileName();
             string projectFilePath = tmpFileName + ".sln";
 
-            string solutionFileContents =
-                """
+            string solutionContents =
+                @"
                 Microsoft Visual Studio Solution File, Format Version 11.00
                 # Visual Studio 2005
                 Project('{E24C65DC-7377-472B-9ABA-BC803B73C61A}') = 'C:\solutions\WebSite2\', '..\..\solutions\WebSite2\', '{F90528C4-6989-4D33-AFE8-F53173597CC2}'
@@ -2023,8 +1959,7 @@ public void TestSkipInvalidConfigurationsCase(bool useNewParser)
                         {F90528C4-6989-4D33-AFE8-F53173597CC2}.Debug|Any CPU.ActiveCfg = Debug|.NET
                         {F90528C4-6989-4D33-AFE8-F53173597CC2}.Debug|Any CPU.Build.0 = Debug|.NET
                     EndGlobalSection
-                EndGlobal
-                """;
+                EndGlobal";
 
             try
             {
@@ -2034,7 +1969,7 @@ public void TestSkipInvalidConfigurationsCase(bool useNewParser)
                 globalProperties["Configuration"] = "Nonexistent";
                 globalProperties["SkipInvalidConfigurations"] = "true";
 
-                SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+                SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionContents.Replace('\'', '"'));
                 ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, globalProperties, null, BuildEventContext.Invalid, CreateMockLoggingService());
                 ProjectInstance msbuildProject = instances[0];
 
@@ -2238,52 +2173,50 @@ public void BadFrameworkMonkierExpectBuildToFail2()
         /// Bug indicated that when a target framework version greater than 4.0 was used then the solution project generator would crash.
         /// this test is to make sure the fix is not regressed.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void TestTargetFrameworkVersionGreaterThan4(bool useNewParser)
+        [Fact]
+        public void TestTargetFrameworkVersionGreaterThan4()
         {
             string tmpFileName = FileUtilities.GetTemporaryFileName();
             string projectFilePath = tmpFileName + ".sln";
 
             string solutionFileContents =
-               """
-                Microsoft Visual Studio Solution File, Format Version 11.00
-                # Visual Studio 2010
-                Project('{E24C65DC-7377-472B-9ABA-BC803B73C61A}') = 'WebSite1', '..\WebSite1\', '{6B8F98F2-C976-4029-9321-5CCD73A174DA}'
-                    ProjectSection(WebsiteProperties) = preProject
-                        TargetFrameworkMoniker = '.NETFramework,Version=v4.34'
-                        Debug.AspNetCompiler.VirtualPath = '/WebSite1'
-                        Debug.AspNetCompiler.PhysicalPath = '..\WebSite1\'
-                        Debug.AspNetCompiler.TargetPath = 'PrecompiledWeb\WebSite1\'
-                        Debug.AspNetCompiler.Updateable = 'true'
-                        Debug.AspNetCompiler.ForceOverwrite = 'true'
-                        Debug.AspNetCompiler.FixedNames = 'false'
-                        Debug.AspNetCompiler.Debug = 'True'
-                        Release.AspNetCompiler.VirtualPath = '/WebSite1'
-                        Release.AspNetCompiler.PhysicalPath = '..\WebSite1\'
-                        Release.AspNetCompiler.TargetPath = 'PrecompiledWeb\WebSite1\'
-                        Release.AspNetCompiler.Updateable = 'true'
-                        Release.AspNetCompiler.ForceOverwrite = 'true'
-                        Release.AspNetCompiler.FixedNames = 'false'
-                        Release.AspNetCompiler.Debug = 'False'
-                        VWDPort = '45602'
-                        DefaultWebSiteLanguage = 'Visual Basic'
-                    EndProjectSection
-                EndProject
-                Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|Any CPU = Debug|Any CPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                        {6B8F98F2-C976-4029-9321-5CCD73A174DA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {6B8F98F2-C976-4029-9321-5CCD73A174DA}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                    EndGlobalSection
-                    GlobalSection(SolutionProperties) = preSolution
-                        HideSolutionNode = FALSE
-                    EndGlobalSection
-                EndGlobal
-                """;
+               @"
+Microsoft Visual Studio Solution File, Format Version 11.00
+# Visual Studio 2010
+Project('{E24C65DC-7377-472B-9ABA-BC803B73C61A}') = 'WebSite1', '..\WebSite1\', '{6B8F98F2-C976-4029-9321-5CCD73A174DA}'
+    ProjectSection(WebsiteProperties) = preProject
+        TargetFrameworkMoniker = '.NETFramework,Version=v4.34'
+        Debug.AspNetCompiler.VirtualPath = '/WebSite1'
+        Debug.AspNetCompiler.PhysicalPath = '..\WebSite1\'
+        Debug.AspNetCompiler.TargetPath = 'PrecompiledWeb\WebSite1\'
+        Debug.AspNetCompiler.Updateable = 'true'
+        Debug.AspNetCompiler.ForceOverwrite = 'true'
+        Debug.AspNetCompiler.FixedNames = 'false'
+        Debug.AspNetCompiler.Debug = 'True'
+        Release.AspNetCompiler.VirtualPath = '/WebSite1'
+        Release.AspNetCompiler.PhysicalPath = '..\WebSite1\'
+        Release.AspNetCompiler.TargetPath = 'PrecompiledWeb\WebSite1\'
+        Release.AspNetCompiler.Updateable = 'true'
+        Release.AspNetCompiler.ForceOverwrite = 'true'
+        Release.AspNetCompiler.FixedNames = 'false'
+        Release.AspNetCompiler.Debug = 'False'
+        VWDPort = '45602'
+        DefaultWebSiteLanguage = 'Visual Basic'
+    EndProjectSection
+EndProject
+Global
+    GlobalSection(SolutionConfigurationPlatforms) = preSolution
+        Debug|Any CPU = Debug|Any CPU
+    EndGlobalSection
+    GlobalSection(ProjectConfigurationPlatforms) = postSolution
+        {6B8F98F2-C976-4029-9321-5CCD73A174DA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+        {6B8F98F2-C976-4029-9321-5CCD73A174DA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+    EndGlobalSection
+    GlobalSection(SolutionProperties) = preSolution
+        HideSolutionNode = FALSE
+    EndGlobalSection
+EndGlobal
+                ";
 
             try
             {
@@ -2293,9 +2226,7 @@ public void TestTargetFrameworkVersionGreaterThan4(bool useNewParser)
                 globalProperties["Configuration"] = "Release";
                 globalProperties["SkipInvalidConfigurations"] = "true";
 
-
-                SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
-
+                SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents.Replace('\'', '"'));
                 using ProjectCollection collection = new ProjectCollection();
                 collection.RegisterLogger(logger);
 
@@ -2325,16 +2256,14 @@ public void TestTargetFrameworkVersionGreaterThan4(bool useNewParser)
         /// <summary>
         /// Verifies that when target names are specified they end up in the metaproj.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void CustomTargetNamesAreInInMetaproj(bool useNewParser)
+        [Fact]
+        public void CustomTargetNamesAreInInMetaproj()
         {
-            string solutionFileContents =
-                """
-                Microsoft Visual Studio Solution File, Format Version 12.00
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(
+            @"
+                Microsoft Visual Studio Solution File, Format Version 14.00
                 # Visual Studio 2015
-                Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ClassLibrary1", "ClassLibrary1.csproj", "{6185CC21-BE89-448A-B3C0-D1C27112E595}"
+                Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""ClassLibrary1"", ""ClassLibrary1.csproj"", ""{6185CC21-BE89-448A-B3C0-D1C27112E595}""
                 EndProject
                 Global
                     GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -2346,9 +2275,7 @@ public void CustomTargetNamesAreInInMetaproj(bool useNewParser)
                         {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = CSConfig2|Any CPU
                     EndGlobalSection
                 EndGlobal
-                """;
-
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            ");
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, null, BuildEventContext.Invalid, CreateMockLoggingService(), new List<string> { "One" });
 
@@ -2377,16 +2304,14 @@ public void CustomTargetNamesAreInInMetaproj(bool useNewParser)
         /// <summary>
         /// Verifies that disambiguated target names are used when a project name matches a standard solution entry point.
         /// </summary>
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public void DisambiguatedTargetNamesAreInMetaproj(bool useNewParser)
+        [Fact]
+        public void DisambiguatedTargetNamesAreInInMetaproj()
         {
-            foreach (string projectName in ProjectInSolution.projectNamesToDisambiguate)
+            foreach(string projectName in ProjectInSolution.projectNamesToDisambiguate)
             {
-                string solutionFileContents =
-                    $$"""
-                    Microsoft Visual Studio Solution File, Format Version 12.00
+                SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(
+                $$"""
+                    Microsoft Visual Studio Solution File, Format Version 14.00
                     # Visual Studio 2015
                     Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "{{projectName}}", "{{projectName}}.csproj", "{6185CC21-BE89-448A-B3C0-D1C27112E595}"
                     EndProject
@@ -2401,9 +2326,7 @@ public void DisambiguatedTargetNamesAreInMetaproj(bool useNewParser)
                             {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
                         EndGlobalSection
                     EndGlobal
-                    """;
-
-                SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+                """);
 
                 ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, null, null, BuildEventContext.Invalid, CreateMockLoggingService(), null);
 
@@ -2426,33 +2349,29 @@ public void DisambiguatedTargetNamesAreInMetaproj(bool useNewParser)
         /// Verifies that illegal user target names (the ones already used internally) don't crash the SolutionProjectGenerator
         /// </summary>
         [Theory]
-        [InlineData(false, false)]
-        [InlineData(true, false)]
-        [InlineData(false, true)]
-        [InlineData(true, true)]
-        public void IllegalUserTargetNamesDoNotThrow(bool forceCaseDifference, bool useNewParser)
+        [InlineData(false)]
+        [InlineData(true)]
+        public void IllegalUserTargetNamesDoNotThrow(bool forceCaseDifference)
         {
-            string solutionFileContents =
-                """
-                Microsoft Visual Studio Solution File, Format Version 12.00
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(
+            @"
+                Microsoft Visual Studio Solution File, Format Version 14.00
                 # Visual Studio 2015
-                Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ClassLibrary1", "ClassLibrary1.csproj", "{6185CC21-BE89-448A-B3C0-D1C27112E595}"
+                Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""ClassLibrary1"", ""ClassLibrary1.csproj"", ""{6185CC21-BE89-448A-B3C0-D1C27112E595}""
                 EndProject
                 Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|Any CPU = Debug|Any CPU
-                        Release|Any CPU = Release|Any CPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
-                    EndGlobalSection
+	                GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		                Debug|Any CPU = Debug|Any CPU
+		                Release|Any CPU = Release|Any CPU
+	                EndGlobalSection
+	                GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
+	                EndGlobalSection
                 EndGlobal
-                """;
-
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            ");
 
             ProjectInstance[] instances;
 
@@ -2507,34 +2426,31 @@ public void AfterTargetsComeFromImport()
         {
             string baseDirectory = Guid.NewGuid().ToString("N");
 
-            string solutionFilePath = ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"{Guid.NewGuid():N}.sln"),
-                """
-                Microsoft Visual Studio Solution File, Format Version 12.00
+            string solutionFilePath = ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"{Guid.NewGuid():N}.sln"), @"
+                Microsoft Visual Studio Solution File, Format Version 14.00
                 # Visual Studio 2015
-                Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ClassLibrary1", "ClassLibrary1.csproj", "{6185CC21-BE89-448A-B3C0-D1C27112E595}"
+                Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""ClassLibrary1"", ""ClassLibrary1.csproj"", ""{6185CC21-BE89-448A-B3C0-D1C27112E595}""
                 EndProject
                 Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|Any CPU = Debug|Any CPU
-                        Release|Any CPU = Release|Any CPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
-                    EndGlobalSection
+	                GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		                Debug|Any CPU = Debug|Any CPU
+		                Release|Any CPU = Release|Any CPU
+	                EndGlobalSection
+	                GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
+	                EndGlobalSection
                 EndGlobal
-                """);
+            ");
 
-            ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"after.{Path.GetFileName(solutionFilePath)}.targets"),
-                """
-                <Project ToolsVersion="msbuilddefaulttoolsversion" xmlns="msbuildnamespace">
-                    <Target Name="MyTarget">
+            ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"after.{Path.GetFileName(solutionFilePath)}.targets"), @"
+                <Project ToolsVersion=""msbuilddefaulttoolsversion"" xmlns=""msbuildnamespace"">
+                    <Target Name=""MyTarget"">
                         <MyTask />
                     </Target>
-                </Project>
-                """);
+                </Project>");
 
             try
             {
@@ -2566,34 +2482,31 @@ public void BeforeTargetsFromImportCanHookDynamicTarget()
         {
             string baseDirectory = Guid.NewGuid().ToString("N");
 
-            string solutionFilePath = ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"{Guid.NewGuid():N}.sln"),
-                """
-                Microsoft Visual Studio Solution File, Format Version 12.00
+            string solutionFilePath = ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"{Guid.NewGuid():N}.sln"), @"
+                Microsoft Visual Studio Solution File, Format Version 14.00
                 # Visual Studio 2015
-                Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ClassLibrary1", "ClassLibrary1.csproj", "{6185CC21-BE89-448A-B3C0-D1C27112E595}"
+                Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""ClassLibrary1"", ""ClassLibrary1.csproj"", ""{6185CC21-BE89-448A-B3C0-D1C27112E595}""
                 EndProject
                 Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|Any CPU = Debug|Any CPU
-                        Release|Any CPU = Release|Any CPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
-                    EndGlobalSection
+	                GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		                Debug|Any CPU = Debug|Any CPU
+		                Release|Any CPU = Release|Any CPU
+	                EndGlobalSection
+	                GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
+	                EndGlobalSection
                 EndGlobal
-                """);
+            ");
 
-            ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"after.{Path.GetFileName(solutionFilePath)}.targets"),
-                """
-                <Project ToolsVersion="msbuilddefaulttoolsversion" xmlns="msbuildnamespace">
-                    <Target Name="MyTarget" BeforeTargets="DynamicTraversalTarget">
-                        <Warning Text="Message from MyTarget" />
+            ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"after.{Path.GetFileName(solutionFilePath)}.targets"), @"
+                <Project ToolsVersion=""msbuilddefaulttoolsversion"" xmlns=""msbuildnamespace"">
+                    <Target Name=""MyTarget"" BeforeTargets=""DynamicTraversalTarget"">
+                        <Warning Text=""Message from MyTarget"" />
                     </Target>
-                </Project>
-                """);
+                </Project>");
 
             try
             {
@@ -2644,55 +2557,48 @@ public void DirectorySolutionPropsTest(string projectName, bool enable)
 
             string baseDirectory = Guid.NewGuid().ToString("N");
 
-            string solutionFilePath = ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"{Guid.NewGuid():N}.sln"),
-                """
-                Microsoft Visual Studio Solution File, Format Version 12.00
+            string solutionFilePath = ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, $"{Guid.NewGuid():N}.sln"), @"
+                Microsoft Visual Studio Solution File, Format Version 14.00
                 # Visual Studio 2015
-                Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ClassLibrary1", "ClassLibrary1.csproj", "{6185CC21-BE89-448A-B3C0-D1C27112E595}"
+                Project(""{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}"") = ""ClassLibrary1"", ""ClassLibrary1.csproj"", ""{6185CC21-BE89-448A-B3C0-D1C27112E595}""
                 EndProject
                 Global
-                    GlobalSection(SolutionConfigurationPlatforms) = preSolution
-                        Debug|Any CPU = Debug|Any CPU
-                        Release|Any CPU = Release|Any CPU
-                    EndGlobalSection
-                    GlobalSection(ProjectConfigurationPlatforms) = postSolution
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.Build.0 = Debug|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = Release|Any CPU
-                        {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
-                    EndGlobalSection
+	                GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		                Debug|Any CPU = Debug|Any CPU
+		                Release|Any CPU = Release|Any CPU
+	                EndGlobalSection
+	                GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		                {6185CC21-BE89-448A-B3C0-D1C27112E595}.Release|Any CPU.Build.0 = Release|Any CPU
+	                EndGlobalSection
                 EndGlobal
-                """);
+            ");
 
-            string projectPath = ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, projectName),
-                $$"""
-                <Project ToolsVersion="msbuilddefaulttoolsversion" xmlns="msbuildnamespace">
+            string projectPath = ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, projectName), $@"
+                <Project ToolsVersion=""msbuilddefaulttoolsversion"" xmlns=""msbuildnamespace"">
                     <PropertyGroup>
-                        <PropertyA>{{expectedPropertyValue}}</PropertyA>
+                        <PropertyA>{expectedPropertyValue}</PropertyA>
                     </PropertyGroup>
-                </Project>
-                """);
+                </Project>");
 
             if (projectPath.StartsWith("Custom", StringComparison.OrdinalIgnoreCase))
             {
                 // If a custom file name was given, create a Directory.Solution.props and Directory.Build.targets to ensure that they aren't imported
-                ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, "Directory.Solution.props"),
-                    """
-                    <Project ToolsVersion="msbuilddefaulttoolsversion" xmlns="msbuildnamespace">
-                        <PropertyGroup>
-                            <PropertyA>This file should not be imported</PropertyA>
-                        </PropertyGroup>
-                    </Project>
-                    """);
-
-                ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, "Directory.Solution.targets"),
-                    """
-                    <Project ToolsVersion="msbuilddefaulttoolsversion" xmlns="msbuildnamespace">
-                        <PropertyGroup>
-                            <PropertyA>This file should not be imported</PropertyA>
-                        </PropertyGroup>
-                    </Project>
-                    """);
+                ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, "Directory.Solution.props"), $@"
+                <Project ToolsVersion=""msbuilddefaulttoolsversion"" xmlns=""msbuildnamespace"">
+                    <PropertyGroup>
+                        <PropertyA>This file should not be imported</PropertyA>
+                    </PropertyGroup>
+                </Project>");
+
+                ObjectModelHelpers.CreateFileInTempProjectDirectory(Path.Combine(baseDirectory, "Directory.Solution.targets"), $@"
+                <Project ToolsVersion=""msbuilddefaulttoolsversion"" xmlns=""msbuildnamespace"">
+                    <PropertyGroup>
+                        <PropertyA>This file should not be imported</PropertyA>
+                    </PropertyGroup>
+                </Project>");
             }
 
             try
@@ -2734,23 +2640,20 @@ public void DirectorySolutionPropsTest(string projectName, bool enable)
         /// Regression test for https://github.com/dotnet/msbuild/issues/6236
         /// </summary>
         [Theory]
-        [InlineData("http://localhost:8080", false)]
-        [InlineData("http://localhost:8080", true)]
-        [InlineData(_longLineString, false)]
-        [InlineData(_longLineString, true)]
-        public void AbsolutePathWorksForUnsupportedPaths(string relativePath, bool useNewParser)
+        [InlineData("http://localhost:8080")]
+        [InlineData("a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-a-really-long-string-")]
+        public void AbsolutePathWorksForUnsupportedPaths(string relativePath)
         {
             string solutionFileContents =
-                $$"""
-                Microsoft Visual Studio Solution File, Format Version 12.00
-                # Visual Studio Version 16
-                VisualStudioVersion = 16.0.31025.194
-                MinimumVisualStudioVersion = 10.0.40219.1
-                Project("{E24C65DC-7377-472B-9ABA-BC803B73C61A}") = "WebSite1", "{{relativePath}}", "{96E0707C-2E9C-4704-946F-FA583147737F}"
-                EndProject
-                """;
+                $@"
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.31025.194
+MinimumVisualStudioVersion = 10.0.40219.1
+Project(""{{E24C65DC-7377-472B-9ABA-BC803B73C61A}}"") = ""WebSite1"", ""{relativePath}"", ""{{{{96E0707C-2E9C-4704-946F-FA583147737F}}}}""
+EndProject";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInSolution projectInSolution = solution.ProjectsInOrder.ShouldHaveSingleItem();
 
@@ -2762,25 +2665,25 @@ public void AbsolutePathWorksForUnsupportedPaths(string relativePath, bool useNe
         /// <summary>
         /// Create a Project derived from a Venus solution
         /// </summary>
-        private ProjectInstance CreateVenusSolutionProject(bool useNewParser)
+        private ProjectInstance CreateVenusSolutionProject()
         {
-            return CreateVenusSolutionProject(null, null, useNewParser);
+            return CreateVenusSolutionProject(null, null);
         }
 
         /// <summary>
         /// Create a Project derived from a Venus solution
         /// </summary>
-        private ProjectInstance CreateVenusSolutionProject(IDictionary<string, string> globalProperties, bool useNewParser)
+        private ProjectInstance CreateVenusSolutionProject(IDictionary<string, string> globalProperties)
         {
-            return CreateVenusSolutionProject(globalProperties, null, useNewParser);
+            return CreateVenusSolutionProject(globalProperties, null);
         }
 
         /// <summary>
         /// Create a Project derived from a Venus solution
         /// </summary>
-        private ProjectInstance CreateVenusSolutionProject(string toolsVersion, bool useNewParser)
+        private ProjectInstance CreateVenusSolutionProject(string toolsVersion)
         {
-            return CreateVenusSolutionProject(null, toolsVersion, useNewParser);
+            return CreateVenusSolutionProject(null, toolsVersion);
         }
 
         /// <summary>
@@ -2789,10 +2692,10 @@ private ProjectInstance CreateVenusSolutionProject(string toolsVersion, bool use
         /// </summary>
         /// <param name="globalProperties">The dictionary of global properties.  May be null.</param>
         /// <param name="toolsVersion">The ToolsVersion override value.  May be null.</param>
-        private ProjectInstance CreateVenusSolutionProject(IDictionary<string, string> globalProperties, string toolsVersion, bool useNewParser)
+        private ProjectInstance CreateVenusSolutionProject(IDictionary<string, string> globalProperties, string toolsVersion)
         {
             string solutionFileContents =
-                """
+                @"
                 Microsoft Visual Studio Solution File, Format Version 9.00
                 # Visual Studio 2005
                 Project('{E24C65DC-7377-472B-9ABA-BC803B73C61A}') = 'C:\solutions\WebSite2\', '..\..\solutions\WebSite2\', '{F90528C4-6989-4D33-AFE8-F53173597CC2}'
@@ -2824,9 +2727,9 @@ private ProjectInstance CreateVenusSolutionProject(IDictionary<string, string> g
                         {F90528C4-6989-4D33-AFE8-F53173597CC2}.Debug|Any CPU.Build.0 = Debug|.NET
                     EndGlobalSection
                 EndGlobal
-                """;
+                ";
 
-            SolutionFile solution = ParseSolutionHelper(solutionFileContents, useNewParser);
+            SolutionFile solution = SolutionFile_Tests.ParseSolutionHelper(solutionFileContents);
 
             ProjectInstance[] instances = SolutionProjectGenerator.Generate(solution, globalProperties, toolsVersion, BuildEventContext.Invalid, CreateMockLoggingService());
 
@@ -2873,12 +2776,6 @@ private void AssertProjectItemNameCount(ProjectInstance msbuildProject, string i
             Assert.Equal(count, itemGroup.Count());
         }
 
-        private SolutionFile ParseSolutionHelper(string solutionFileContents, bool useNewParser)
-        {
-            return useNewParser ? SolutionFile_NewParser_Tests.ParseSolutionHelper(solutionFileContents) :
-                SolutionFile_OldParser_Tests.ParseSolutionHelper(solutionFileContents);
-        }
-
         #endregion // Helper Functions
     }
 }
diff --git a/src/Build.UnitTests/Evaluation/Preprocessor_Tests.cs b/src/Build.UnitTests/Evaluation/Preprocessor_Tests.cs
index da04dae2a84..b6b49388ec7 100644
--- a/src/Build.UnitTests/Evaluation/Preprocessor_Tests.cs
+++ b/src/Build.UnitTests/Evaluation/Preprocessor_Tests.cs
@@ -933,6 +933,7 @@ This import was added implicitly because the Project element's Sdk attribute spe
         }
 
         [Fact]
+        [ActiveIssue("https://github.com/dotnet/msbuild/issues/11498")]
         public void SdkResolverItemsAndPropertiesAreInPreprocessedOutput()
         {
             using (TestEnvironment env = TestEnvironment.Create())
diff --git a/src/Build.UnitTests/Graph/GetCompatiblePlatformGraph_Tests.cs b/src/Build.UnitTests/Graph/GetCompatiblePlatformGraph_Tests.cs
index d6344240f1a..b941649ad74 100644
--- a/src/Build.UnitTests/Graph/GetCompatiblePlatformGraph_Tests.cs
+++ b/src/Build.UnitTests/Graph/GetCompatiblePlatformGraph_Tests.cs
@@ -402,14 +402,14 @@ public void SolutionWithoutAllConfigurations()
 
                 // Slashes here (and in the .slnf) are hardcoded as backslashes intentionally to support the common case.
                 TransientTestFile solutionFile = testEnvironment.CreateFile(folder, "SimpleProject.sln",
-                    """
+                    @"
                     Microsoft Visual Studio Solution File, Format Version 12.00
                     # Visual Studio Version 16
                     VisualStudioVersion = 16.0.29326.124
                     MinimumVisualStudioVersion = 10.0.40219.1
-                    Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Project1", "1\1\1.csproj", "{79B5EBA6-5D27-4976-BC31-14422245A59A}"
+                    Project(""{9A19103F-16F7-4668-BE54-9A1E7A4F7556}"") = ""Project1"", ""1\1\1.csproj"", ""{79B5EBA6-5D27-4976-BC31-14422245A59A}""
                     EndProject
-                    Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "2", "2\2\2.proj", "{8EFCCA22-9D51-4268-90F7-A595E11FCB2D}"
+                    Project(""{9A19103F-16F7-4668-BE54-9A1E7A4F7556}"") = ""2"", ""2\2\2.proj"", ""{8EFCCA22-9D51-4268-90F7-A595E11FCB2D}""
                     EndProject
                     Global
                         GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -434,7 +434,7 @@ public void SolutionWithoutAllConfigurations()
                             SolutionGuid = {DE7234EC-0C4D-4070-B66A-DCF1B4F0CFEF}
                         EndGlobalSection
                     EndGlobal
-                    """);
+                ");
 
                 ProjectCollection projectCollection = testEnvironment.CreateProjectCollection().Collection;
                 MockLogger logger = new();
diff --git a/src/Build.UnitTests/Graph/GraphLoadedFromSolution_tests.cs b/src/Build.UnitTests/Graph/GraphLoadedFromSolution_tests.cs
index 6d535479b1e..431ea412875 100644
--- a/src/Build.UnitTests/Graph/GraphLoadedFromSolution_tests.cs
+++ b/src/Build.UnitTests/Graph/GraphLoadedFromSolution_tests.cs
@@ -59,8 +59,7 @@ public void GraphConstructionFailsOnNonExistentSolution()
                     new ProjectGraph("nonExistent.sln");
                 });
 
-            exception.Message.ShouldContain("The project file could not be loaded.");
-            exception.Message.ShouldContain("Could not find file");
+            exception.Message.ShouldContain("The project file could not be loaded. Could not find file");
         }
 
         [Fact]
@@ -647,6 +646,28 @@ IEnumerable<ProjectItemInstance> GetIncomingEdgeItemsToNode(ProjectGraphNode nod
             }
         }
 
+        [Fact]
+        public void GraphConstructionShouldThrowOnMissingSolutionDependencies()
+        {
+            var solutionContents = SolutionFileBuilder.FromGraphEdges(
+                _env,
+                new Dictionary<int, int[]> { { 1, null }, { 2, null } },
+                new[] { ("1", new[] { Guid.NewGuid().ToString("B") }) }).BuildSolution();
+
+            var solutionFile = _env.CreateFile(
+                "solution.sln",
+                solutionContents)
+                .Path;
+
+            var exception = Should.Throw<InvalidProjectFileException>(
+                () =>
+                {
+                    new ProjectGraph(solutionFile);
+                });
+
+            exception.Message.ShouldContain("but a project with this GUID was not found in the .SLN file");
+        }
+
         private static bool IsSolutionItemReference(ProjectItemInstance edgeItem)
         {
             return edgeItem.ItemType == GraphBuilder.SolutionItemReference;
diff --git a/src/Build/Construction/ProjectRootElement.cs b/src/Build/Construction/ProjectRootElement.cs
index cc416e5d409..eee48e9f667 100644
--- a/src/Build/Construction/ProjectRootElement.cs
+++ b/src/Build/Construction/ProjectRootElement.cs
@@ -176,6 +176,14 @@ internal ProjectRootElement(XmlReader xmlReader, ProjectRootElementCacheBase pro
             ProjectParser.Parse(document, this);
         }
 
+        private readonly bool _isEphemeral = false;
+
+        private ProjectRootElement(ProjectRootElementCacheBase projectRootElementCache, NewProjectFileOptions projectFileOptions, bool isEphemeral)
+            : this(projectRootElementCache, projectFileOptions)
+        {
+            _isEphemeral = isEphemeral;
+        }
+
         /// <summary>
         /// Initialize an in-memory, empty ProjectRootElement instance that can be saved later.
         /// Leaves the project dirty, indicating there are unsaved changes.
@@ -321,6 +329,8 @@ public override string Condition
         /// </summary>
         public ICollection<ProjectImportElement> Imports => new ReadOnlyCollection<ProjectImportElement>(GetAllChildrenOfType<ProjectImportElement>());
 
+        internal bool IsEphemeral => _isEphemeral;
+
         /// <summary>
         /// Get a read-only collection of the child property groups, if any.
         /// Does not include any that may not be at the root, i.e. inside Choose elements.
@@ -712,6 +722,18 @@ internal ProjectExtensionsElement ProjectExtensions
         internal string LastDirtyReason
             => _dirtyReason == null ? null : String.Format(CultureInfo.InvariantCulture, _dirtyReason, _dirtyParameter);
 
+        /// <summary>
+        /// Initialize an in-memory empty ProjectRootElement instance that CANNOT be saved later.
+        /// The ProjectRootElement will not be marked dirty.
+        /// Uses the global project collection.
+        /// </summary>
+        internal static ProjectRootElement CreateEphemeral(ProjectRootElementCacheBase projectRootElementCache)
+        {
+            ErrorUtilities.VerifyThrowArgumentNull(projectRootElementCache);
+
+            return new ProjectRootElement(projectRootElementCache, Project.DefaultNewProjectTemplateOptions, isEphemeral: true);
+        }
+
         /// <summary>
         /// Initialize an in-memory, empty ProjectRootElement instance that can be saved later.
         /// Uses the global project collection.
@@ -1817,6 +1839,11 @@ internal override void VerifyThrowInvalidOperationAcceptableLocation(ProjectElem
         /// </remarks>
         internal sealed override void MarkDirty(string reason, string param)
         {
+            if (_isEphemeral)
+            {
+                return;
+            }
+
             if (Link != null)
             {
                 RootLink.MarkDirty(reason, param);
diff --git a/src/Build/Construction/Solution/SolutionFile.cs b/src/Build/Construction/Solution/SolutionFile.cs
index 63ce5b9dcee..b549e97da5a 100644
--- a/src/Build/Construction/Solution/SolutionFile.cs
+++ b/src/Build/Construction/Solution/SolutionFile.cs
@@ -193,7 +193,7 @@ internal int VisualStudioVersion
 
         internal bool UseNewParser => ShouldUseNewParser(_solutionFile);
 
-        internal static bool ShouldUseNewParser(string solutionFile) => ChangeWaves.AreFeaturesEnabled(ChangeWaves.Wave17_14) || FileUtilities.IsSolutionXFilename(solutionFile);
+        internal static bool ShouldUseNewParser(string solutionFile) => FileUtilities.IsSolutionXFilename(solutionFile);
 
         /// <summary>
         /// All projects in this solution, in the order they appeared in the solution file
@@ -221,10 +221,6 @@ internal string FullPath
 
             set
             {
-                if (ChangeWaves.AreFeaturesEnabled(ChangeWaves.Wave17_14) && string.IsNullOrEmpty(value))
-                {
-                    throw new ArgumentNullException(nameof(FullPath));
-                }
                 // Should already be canonicalized to a full path
                 ErrorUtilities.VerifyThrowInternalRooted(value);
                 // To reduce code duplication, this should be
diff --git a/src/Build/Definition/Project.cs b/src/Build/Definition/Project.cs
index 1348a7cffcc..2401d4935a1 100644
--- a/src/Build/Definition/Project.cs
+++ b/src/Build/Definition/Project.cs
@@ -2257,7 +2257,7 @@ public override IList<ResolvedImport> Imports
 
                     foreach (ResolvedImport import in _data.ImportClosure)
                     {
-                        if (import.ImportingElement != null) // Exclude outer project itself
+                        if (import.ImportingElement != null && !import.ImportedProject.IsEphemeral) // Exclude outer project itself and SDK-resolver synthesized imports
                         {
                             imports.Add(import);
                         }
@@ -2280,7 +2280,7 @@ public override IList<ResolvedImport> ImportsIncludingDuplicates
 
                     foreach (var import in _data.ImportClosureWithDuplicates)
                     {
-                        if (import.ImportingElement != null) // Exclude outer project itself
+                        if (import.ImportingElement != null && !import.ImportedProject.IsEphemeral) // Exclude outer project itself and SDK-resolver synthesized imports
                         {
                             imports.Add(import);
                         }
diff --git a/src/Build/Evaluation/Evaluator.cs b/src/Build/Evaluation/Evaluator.cs
index e285a948aa4..cba4152a3fc 100644
--- a/src/Build/Evaluation/Evaluator.cs
+++ b/src/Build/Evaluation/Evaluator.cs
@@ -1931,7 +1931,7 @@ private ProjectRootElement CreateProjectForSdkResult(SdkResult sdkResult)
 
             ProjectRootElement InnerCreate(string _, ProjectRootElementCacheBase __)
             {
-                ProjectRootElement project = ProjectRootElement.Create();
+                ProjectRootElement project = ProjectRootElement.CreateEphemeral(_projectRootElementCache);
                 project.FullPath = projectPath;
 
                 if (sdkResult.PropertiesToAdd?.Any() == true)