diff --git a/docs/core/compatibility/3.1-5.0.md b/docs/core/compatibility/3.1-5.0.md
index 2624ae2372098..55d868cf45e2a 100644
--- a/docs/core/compatibility/3.1-5.0.md
+++ b/docs/core/compatibility/3.1-5.0.md
@@ -58,11 +58,16 @@ If you're migrating from version 3.1 of .NET Core, ASP.NET Core, or EF Core to v
 ## Core .NET libraries
 
 - [SSE and SSE2 CompareGreaterThan methods properly handle NaN inputs](#sse-and-sse2-comparegreaterthan-methods-properly-handle-nan-inputs)
+- [CounterSet.CreateCounterSetInstance now throws InvalidOperationException if instance already exist](#countersetcreatecountersetinstance-now-throws-invalidoperationexception-if-instance-already-exists)
 
 [!INCLUDE [sse-comparegreaterthan-intrinsics](../../../includes/core-changes/corefx/5.0/sse-comparegreaterthan-intrinsics.md)]
 
 ***
 
+[!INCLUDE [createcountersetinstance-throws-invalidoperation](../../../includes/core-changes/corefx/5.0/createcountersetinstance-throws-invalidoperation.md)]
+
+***
+
 ## Globalization
 
 - [StringInfo and TextElementEnumerator are now UAX29-compliant](#stringinfo-and-textelementenumerator-are-now-uax29-compliant)
diff --git a/docs/core/compatibility/corefx.md b/docs/core/compatibility/corefx.md
index cd75230c408a8..d73c7df97bd53 100644
--- a/docs/core/compatibility/corefx.md
+++ b/docs/core/compatibility/corefx.md
@@ -12,6 +12,7 @@ The following breaking changes are documented on this page:
 | Breaking change | Version introduced |
 | - | :-: |
 | [SSE and SSE2 CompareGreaterThan methods properly handle NaN inputs](#sse-and-sse2-comparegreaterthan-methods-properly-handle-nan-inputs) | 5.0 |
+| [CounterSet.CreateCounterSetInstance now throws InvalidOperationException if instance already exist](#countersetcreatecountersetinstance-now-throws-invalidoperationexception-if-instance-already-exists) | 5.0 |
 | [APIs that report version now report product and not file version](#apis-that-report-version-now-report-product-and-not-file-version) | 3.0 |
 | [Custom EncoderFallbackBuffer instances cannot fall back recursively](#custom-encoderfallbackbuffer-instances-cannot-fall-back-recursively) | 3.0 |
 | [Floating point formatting and parsing behavior changes](#floating-point-formatting-and-parsing-behavior-changed) | 3.0 |
@@ -40,6 +41,10 @@ The following breaking changes are documented on this page:
 
 ***
 
+[!INCLUDE [createcountersetinstance-throws-invalidoperation](../../../includes/core-changes/corefx/5.0/createcountersetinstance-throws-invalidoperation.md)]
+
+***
+
 ## .NET Core 3.0
 
 [!INCLUDE[APIs that report version now report product and not file version](~/includes/core-changes/corefx/3.0/version-information-changes.md)]
diff --git a/includes/core-changes/corefx/5.0/createcountersetinstance-throws-invalidoperation.md b/includes/core-changes/corefx/5.0/createcountersetinstance-throws-invalidoperation.md
new file mode 100644
index 0000000000000..f710c95a559a7
--- /dev/null
+++ b/includes/core-changes/corefx/5.0/createcountersetinstance-throws-invalidoperation.md
@@ -0,0 +1,36 @@
+### CounterSet.CreateCounterSetInstance now throws InvalidOperationException if instance already exists
+
+Starting in .NET 5.0, <xref:System.Diagnostics.PerformanceData.CounterSet.CreateCounterSetInstance(System.String)?displayProperty=nameWithType> throws an <xref:System.InvalidOperationException> instead of an <xref:System.ArgumentException> if the counter set already exists.
+
+#### Change description
+
+In .NET Framework and .NET Core 1.0 to 3.1, you can create an instance of the counter set by calling <xref:System.Diagnostics.PerformanceData.CounterSet.CreateCounterSetInstance%2A>. However, if the counter set already exists, the method throws an <xref:System.ArgumentException> exception.
+
+In .NET 5.0 and later versions, when you call <xref:System.Diagnostics.PerformanceData.CounterSet.CreateCounterSetInstance%2A> and the counter set exists, an <xref:System.InvalidOperationException> exception is thrown.
+
+#### Version introduced
+
+5.0 Preview 5
+
+#### Recommended action
+
+If you catch <xref:System.ArgumentException> exceptions in your app when calling <xref:System.Diagnostics.PerformanceData.CounterSet.CreateCounterSetInstance%2A>, consider also catching <xref:System.InvalidOperationException> exceptions.
+
+> [!NOTE]
+> Catching <xref:System.ArgumentException> exceptions is not recommended.
+
+#### Category
+
+Core .NET libraries
+
+#### Affected APIs
+
+- <xref:System.Diagnostics.PerformanceData.CounterSet.CreateCounterSetInstance%2A?displayProperty=fullName>
+
+<!--
+
+#### Affected APIs
+
+- `M:System.Diagnostics.PerformanceData.CounterSet.CreateCounterSetInstance(System.String)`
+
+-->