diff --git a/src/libraries/Common/src/System/Experimentals.cs b/src/libraries/Common/src/System/Experimentals.cs
index dea16867104820..f96dde8960d7d6 100644
--- a/src/libraries/Common/src/System/Experimentals.cs
+++ b/src/libraries/Common/src/System/Experimentals.cs
@@ -28,8 +28,7 @@ internal static class Experimentals
// X86Base.DivRem is experimental since performance is not as optimized as T.DivRem
internal const string X86BaseDivRemDiagId = "SYSLIB5004";
- // System.Formats.Nrbf is experimental
- internal const string NrbfDecoderDiagId = "SYSLIB5005";
+ // System.Formats.Nrbf was experimental, do not reuse "SYSLIB5005"
// When adding a new diagnostic ID, add it to the table in docs\project\list-of-diagnostics.md as well.
// Keep new const identifiers above this comment.
diff --git a/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.Experimental.cs b/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.Experimental.cs
deleted file mode 100644
index 7c8b580a721ae0..00000000000000
--- a/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.Experimental.cs
+++ /dev/null
@@ -1,4 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-[assembly: System.Diagnostics.CodeAnalysis.ExperimentalAttribute("SYSLIB5005", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
diff --git a/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.csproj b/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.csproj
index 1fcac9238bc8f7..5965de282a307e 100644
--- a/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.csproj
+++ b/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.csproj
@@ -13,11 +13,6 @@
-
-
-
-
diff --git a/src/libraries/System.Formats.Nrbf/src/AssemblyInfo.cs b/src/libraries/System.Formats.Nrbf/src/AssemblyInfo.cs
deleted file mode 100644
index d976cf786d901a..00000000000000
--- a/src/libraries/System.Formats.Nrbf/src/AssemblyInfo.cs
+++ /dev/null
@@ -1,7 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-using System;
-using System.Diagnostics.CodeAnalysis;
-
-[assembly: Experimental(Experimentals.NrbfDecoderDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
diff --git a/src/libraries/System.Formats.Nrbf/src/PACKAGE.md b/src/libraries/System.Formats.Nrbf/src/PACKAGE.md
index 23e5ac389d3d14..d1211ec938d254 100644
--- a/src/libraries/System.Formats.Nrbf/src/PACKAGE.md
+++ b/src/libraries/System.Formats.Nrbf/src/PACKAGE.md
@@ -6,8 +6,6 @@
You can think of [NrbfDecoder](https://learn.microsoft.com/en-us/dotnet/api/system.formats.nrbf.nrbfdecoder) as being the equivalent of using a JSON/XML reader without the deserializer.
-**Note:** The 9.0.0 release of the `System.Formats.Nrbf` package is marked `[Experimental]` as the API shape is subject to change in the next major release. Even with the experimental annotation, the package is officially supported. Using the APIs from this package will produce a build warning with diagnostic ID `SYSLIB5005`. The diagnostic can be suppressed with the acknowledgement that the API shape is subject to change in the next major release.
-
## How to Use
The NRBF payload consists of serialization records that represent the serialized objects and their metadata. To read the whole payload and get the root record, you need to call one of the [NrbfDecoder.Decode](https://learn.microsoft.com/dotnet/api/system.formats.nrbf.nrbfdecoder.decode) methods.
diff --git a/src/libraries/System.Formats.Nrbf/src/System.Formats.Nrbf.csproj b/src/libraries/System.Formats.Nrbf/src/System.Formats.Nrbf.csproj
index 5b4cdd65ec82ee..75df3e54d48eae 100644
--- a/src/libraries/System.Formats.Nrbf/src/System.Formats.Nrbf.csproj
+++ b/src/libraries/System.Formats.Nrbf/src/System.Formats.Nrbf.csproj
@@ -12,14 +12,6 @@
should be removed in order to re-enable validation. -->
true
-
-
-
-
-
-
diff --git a/src/libraries/System.Formats.Nrbf/tests/System.Formats.Nrbf.Tests.csproj b/src/libraries/System.Formats.Nrbf/tests/System.Formats.Nrbf.Tests.csproj
index 9bf2f51fcce6cd..c31537bb983ef1 100644
--- a/src/libraries/System.Formats.Nrbf/tests/System.Formats.Nrbf.Tests.csproj
+++ b/src/libraries/System.Formats.Nrbf/tests/System.Formats.Nrbf.Tests.csproj
@@ -3,8 +3,6 @@
$(NetCoreAppCurrent);$(NetFrameworkMinimum)
true
-
- $(NoWarn);SYSLIB5005
diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis/ExperimentalAttribute.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis/ExperimentalAttribute.cs
index 65429998ab5912..bd6052465590aa 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis/ExperimentalAttribute.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis/ExperimentalAttribute.cs
@@ -22,12 +22,7 @@ namespace System.Diagnostics.CodeAnalysis
AttributeTargets.Event |
AttributeTargets.Interface |
AttributeTargets.Delegate, Inherited = false)]
-#if SYSTEM_PRIVATE_CORELIB
- public
-#else
- internal
-#endif
- sealed class ExperimentalAttribute : Attribute
+ public sealed class ExperimentalAttribute : Attribute
{
///
/// Initializes a new instance of the class, specifying the ID that the compiler will use
diff --git a/src/libraries/System.Resources.Extensions/src/System.Resources.Extensions.csproj b/src/libraries/System.Resources.Extensions/src/System.Resources.Extensions.csproj
index cbd4f4e2ff03f5..64a8ff083423f4 100644
--- a/src/libraries/System.Resources.Extensions/src/System.Resources.Extensions.csproj
+++ b/src/libraries/System.Resources.Extensions/src/System.Resources.Extensions.csproj
@@ -16,8 +16,6 @@ System.Resources.Extensions.DeserializingResourceReader
System.Resources.Extensions.PreserializedResourceWriter
false
-
- $(NoWarn);SYSLIB5005
diff --git a/src/libraries/System.Resources.Extensions/tests/BinaryFormatTests/System.Resources.Extensions.BinaryFormat.Tests.csproj b/src/libraries/System.Resources.Extensions/tests/BinaryFormatTests/System.Resources.Extensions.BinaryFormat.Tests.csproj
index 72b7668c724eb5..c77f6e932d59a7 100644
--- a/src/libraries/System.Resources.Extensions/tests/BinaryFormatTests/System.Resources.Extensions.BinaryFormat.Tests.csproj
+++ b/src/libraries/System.Resources.Extensions/tests/BinaryFormatTests/System.Resources.Extensions.BinaryFormat.Tests.csproj
@@ -11,9 +11,8 @@
SYSLIB0011: BinaryFormatter obsolete
SYSLIB0050: Obsolete attribute
SYSLIB0051: Formatters obsolete
- SYSLIB5005: System.Formats.Nrbf experimental
-->
- $(NoWarn);CS1574;CS1580;CA1036;CA1051;CA1066;SYSLIB0011;SYSLIB0050;SYSLIB0051;SYSLIB5005;xUnit1013;CS0649
+ $(NoWarn);CS1574;CS1580;CA1036;CA1051;CA1066;SYSLIB0011;SYSLIB0050;SYSLIB0051;xUnit1013;CS0649
$(LibrariesProjectRoot)\System.Resources.Extensions\src\Resources\Strings.resx