Microsoft.Extensions.FileProviders.Embedded Fails in .NET 10 with InvalidOperationException

[PikachuCN]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When migrating a project that uses Microsoft.Extensions.FileProviders.Embedded from .NET 8 to .NET 10, the application fails at runtime with a System.InvalidOperationException. The build process also generates a warning suggesting the package may no longer be necessary.

This functionality worked correctly in .NET 8 but is broken after upgrading to the .NET 10 RC.

Expected Behavior

The application should start and serve the files embedded from the wwwroot directory, just as it did in .NET 8.

Steps To Reproduce

Create a new ASP.NET Core Web Application targeting .NET 10.

Modify the .csproj file to include the following settings to embed the wwwroot folder:

XML

<PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <GenerateEmbeddedFilesManifest>true</GenerateEmbeddedFilesManifest>
</PropertyGroup>

<ItemGroup>
    <EmbeddedResource Include="wwwroot\**" />
</ItemGroup>

<ItemGroup>
    <PackageReference Include="Microsoft.Extensions.FileProviders.Embedded" Version="10.0.0-rc.1.25451.107" />
</ItemGroup>

Use the following code in Program.cs to serve the embedded files:

C#

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.UseFileServer(new FileServerOptions
{
RequestPath = "",
FileProvider = new Microsoft.Extensions.FileProviders.ManifestEmbeddedFileProvider(
typeof(Program).Assembly, "wwwroot"
)
});

app.Run();

The application fails to start with the following runtime exception:

System.InvalidOperationException: “Could not load the embedded file manifest 'Microsoft.Extensions.FileProviders.Embedded.Manifest.xml' for assembly 'NetProbe'.”
A build warning is displayed:

PackageReference 'Microsoft.Extensions.FileProviders.Embedded' will not be removed. Consider removing this package from your dependencies as it may not be needed.

Exceptions (if any)

No response

.NET Version

10.0.100-rc.1.25451.107

Anything else?

No response

[jozkee]

For some reason the manifest file is not being included when building targeting 10. It is included when targeting 9. However, it is also not included (in 9) if the nuget package is removed, and the app builds with the Microsoft.Extensions.FileProviders.Embedded assembly from shared.

This looks like a regression.

[anthonymastreanvae]

This blocks us from adopting RC 1 for a pretty straightforward AspNetCore web app (web API and some MVC endpoints). It puts us off adopting the GA until we see how stable it is for the wider industry. Will this be scheduled for fixing in RC 2?

[jozkee]

@danmoseley @sebastienros @wtgodbe