dotnet · Lordfirespeed · May 5, 2025 · May 5, 2025 · May 5, 2025 · May 5, 2025
diff --git a/src/libraries/Common/src/System/IO/ReadOnlyMemoryStream.cs b/src/libraries/Common/src/System/IO/ReadOnlyMemoryStream.cs
@@ -132,14 +132,22 @@ public override Task<int> ReadAsync(byte[] buffer, int offset, int count, Cancel
                 Task.FromResult(ReadBuffer(new Span<byte>(buffer, offset, count)));
         }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !NETFRAMEWORK && !NETSTANDARD2_0 && !NETSTANDARD2_1
         public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default(CancellationToken))
         {
             EnsureNotClosed();
             return cancellationToken.IsCancellationRequested ?
                 ValueTask.FromCanceled<int>(cancellationToken) :
                 new ValueTask<int>(ReadBuffer(buffer.Span));
         }
+#elif NETSTANDARD2_1
+        public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default(CancellationToken))
+        {
+            EnsureNotClosed();
+            return cancellationToken.IsCancellationRequested ?
+                new ValueTask<int>(Task.FromCanceled<int>(cancellationToken)) :
+                new ValueTask<int>(ReadBuffer(buffer.Span));
+        }
 #endif
 
         public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback? callback, object? state) =>
@@ -151,7 +159,7 @@ public override int EndRead(IAsyncResult asyncResult)
             return TaskToAsyncResult.End<int>(asyncResult);
         }
 
-#if !NETFRAMEWORK && !NETSTANDARD2_0
+#if !NETFRAMEWORK && !NETSTANDARD2_0 && !NETSTANDARD2_1
         public override void CopyTo(Stream destination, int bufferSize)
         {
             ValidateCopyToArguments(destination, bufferSize);
@@ -195,7 +203,7 @@ protected override void Dispose(bool disposing)
             base.Dispose(disposing);
         }
 
-#if NETFRAMEWORK || NETSTANDARD2_0
+#if NETFRAMEWORK || NETSTANDARD2_0 || NETSTANDARD2_1
         private static void ValidateBufferArguments(byte[] buffer, int offset, int count)
         {
             ArgumentNullException.ThrowIfNull(buffer);

diff --git a/src/libraries/System.Collections.Immutable/ref/System.Collections.Immutable.csproj b/src/libraries/System.Collections.Immutable/ref/System.Collections.Immutable.csproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
@@ -28,7 +28,11 @@
     <ProjectReference Include="$(LibrariesProjectRoot)System.Runtime\ref\System.Runtime.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>
 

diff --git a/src/libraries/System.Collections.Immutable/src/System.Collections.Immutable.csproj b/src/libraries/System.Collections.Immutable/src/System.Collections.Immutable.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile>
     <IsPackable>true</IsPackable>
@@ -177,9 +177,18 @@ The System.Collections.Immutable library is built-in as part of the shared frame
     <Reference Include="System.Threading" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.1'">
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
+  </ItemGroup>
+
 </Project>
diff --git a/...raries/System.Diagnostics.DiagnosticSource/ref/System.Diagnostics.DiagnosticSource.csproj b/...raries/System.Diagnostics.DiagnosticSource/ref/System.Diagnostics.DiagnosticSource.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
@@ -22,12 +22,13 @@
     <ProjectReference Include="$(LibrariesProjectRoot)System.Runtime\ref\System.Runtime.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+    <Reference Include="System.Runtime" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
-    <Reference Include="System.Runtime" />
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>
 
 </Project>
diff --git a/...raries/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj b/...raries/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <NoWarn>$(NoWarn);SA1205</NoWarn>
     <EnableTrimAnalyzer Condition="$([MSBuild]::GetTargetFrameworkIdentifier('$(TargetFramework)')) == '.NETFramework'">false</EnableTrimAnalyzer>
@@ -135,7 +135,8 @@ System.Diagnostics.DiagnosticSource</PackageDescription>
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' or
-                        '$(TargetFramework)' == 'netstandard2.0'">
+                        '$(TargetFramework)' == 'netstandard2.0' or
+                        '$(TargetFramework)' == 'netstandard2.1'">
     <Compile Include="System\Diagnostics\Activity.DateTime.corefx.cs" />
   </ItemGroup>
 
@@ -161,11 +162,20 @@ System.Diagnostics.DiagnosticSource</PackageDescription>
     <Reference Include="System.Threading.ThreadPool" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.1'">
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="Microsoft.DotNet.Build.Tasks.Templating" Version="$(MicrosoftDotNetBuildTasksTemplatingVersion)" PrivateAssets="All" IsImplicitlyDefined="true" />
   </ItemGroup>

diff --git a/src/libraries/System.Formats.Asn1/ref/System.Formats.Asn1.csproj b/src/libraries/System.Formats.Asn1/ref/System.Formats.Asn1.csproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
@@ -13,7 +13,11 @@
     <ProjectReference Include="$(LibrariesProjectRoot)System.Runtime.Numerics\ref\System.Runtime.Numerics.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>
 </Project>
diff --git a/src/libraries/System.Formats.Asn1/src/System.Formats.Asn1.csproj b/src/libraries/System.Formats.Asn1/src/System.Formats.Asn1.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <DefineConstants>$(DefineConstants);CP_NO_ZEROMEMORY</DefineConstants>
     <IsPackable>true</IsPackable>
@@ -62,13 +62,17 @@
     <Reference Include="System.Text.Encoding.Extensions" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
-    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
+    <Reference Include="System.Numerics" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
     <PackageReference Include="System.ValueTuple" Version="$(SystemValueTupleVersion)" />
-    <Reference Include="System.Numerics" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>
 
 </Project>
diff --git a/src/libraries/System.Formats.Cbor/ref/System.Formats.Cbor.csproj b/src/libraries/System.Formats.Cbor/ref/System.Formats.Cbor.csproj
@@ -1,14 +1,18 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup>
     <Compile Include="System.Formats.Cbor.cs" />
     <Compile Include="System.Formats.Cbor.netcoreapp.cs" Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>
 </Project>
diff --git a/src/libraries/System.Formats.Cbor/src/System.Formats.Cbor.csproj b/src/libraries/System.Formats.Cbor/src/System.Formats.Cbor.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsPackable>true</IsPackable>
     <PackageDescription>Provides classes that can read and write the CBOR data format.
@@ -43,22 +43,30 @@ System.Formats.Cbor.CborWriter</PackageDescription>
     <Compile Include="System\Formats\Cbor\Reader\CborReader.Simple.netcoreapp.cs" />
     <Compile Include="System\Formats\Cbor\Writer\CborWriter.Simple.netcoreapp.cs" />
   </ItemGroup>
-  
+
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
     <Compile Include="System\Formats\Cbor\CborHelpers.netstandard.cs" />
     <Compile Include="System\Formats\Cbor\HalfHelpers.netstandard.cs" />
     <Compile Include="System\Formats\Cbor\Writer\CborWriter.Simple.netstandard.cs" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
     <PackageReference Include="System.Buffers" Version="$(SystemBuffersVersion)" />
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+    <PackageReference Include="System.ValueTuple" Version="$(SystemValueTupleVersion)" />
     <PackageReference Include="Microsoft.Bcl.HashCode" Version="$(MicrosoftBclHashCodeVersion)" />
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
-    <PackageReference Include="System.ValueTuple" Version="$(SystemValueTupleVersion)" />
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+    <PackageReference Include="System.Buffers" Version="$(SystemBuffersVersion)" />
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+    <PackageReference Include="Microsoft.Bcl.HashCode" Version="$(MicrosoftBclHashCodeVersion)" />
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.1'">
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
   </ItemGroup>
 
 </Project>
diff --git a/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.csproj b/src/libraries/System.Formats.Nrbf/ref/System.Formats.Nrbf.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
     <CLSCompliant>false</CLSCompliant>
   </PropertyGroup>
 
@@ -15,6 +15,13 @@
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\RequiresDynamicCodeAttribute.cs" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>
 

diff --git a/src/libraries/System.Formats.Nrbf/src/System.Formats.Nrbf.csproj b/src/libraries/System.Formats.Nrbf/src/System.Formats.Nrbf.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
     <EnableDefaultItems>true</EnableDefaultItems>
     <CLSCompliant>false</CLSCompliant>
     <IsPackable>true</IsPackable>
@@ -12,15 +12,22 @@
          should be removed in order to re-enable validation. -->
     <DisablePackageBaselineValidation>true</DisablePackageBaselineValidation>
   </PropertyGroup>
+
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\RequiresDynamicCodeAttribute.cs"
+         Link="System\Diagnostics\CodeAnalysis\RequiresDynamicCodeAttribute.cs" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFramework)' != '$(NetCoreAppCurrent)'">
     <ProjectReference Include="$(LibrariesProjectRoot)\System.Reflection.Metadata\src\System.Reflection.Metadata.csproj" />
   </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
     <PackageReference Include="System.ValueTuple" Version="$(SystemValueTupleVersion)" />
+    <PackageReference Include="Microsoft.Bcl.HashCode" Version="$(MicrosoftBclHashCodeVersion)" />
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
-    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\RequiresDynamicCodeAttribute.cs"
-         Link="System\Diagnostics\CodeAnalysis\RequiresDynamicCodeAttribute.cs" />
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="Microsoft.Bcl.HashCode" Version="$(MicrosoftBclHashCodeVersion)" />
   </ItemGroup>
 </Project>
diff --git a/src/libraries/System.Formats.Nrbf/src/System/Formats/Nrbf/ClassInfo.cs b/src/libraries/System.Formats.Nrbf/src/System/Formats/Nrbf/ClassInfo.cs
@@ -59,7 +59,7 @@ internal static ClassInfo Decode(BinaryReader reader)
             // however it's impossible to get such output with BinaryFormatter,
             // so we prohibit that on purpose.
             string memberName = reader.ReadString();
-#if NET
+#if !NETFRAMEWORK && !NETSTANDARD2_0
             if (memberNames.TryAdd(memberName, i))
             {
                 continue;

diff --git a/src/libraries/System.Formats.Nrbf/src/System/Formats/Nrbf/RecordMap.cs b/src/libraries/System.Formats.Nrbf/src/System/Formats/Nrbf/RecordMap.cs
@@ -44,7 +44,7 @@ internal void Add(SerializationRecord record)
             }
             else
             {
-#if NET
+#if !NETFRAMEWORK && !NETSTANDARD2_0
                 if (_map.TryAdd(record.Id, record))
                 {
                     return;

diff --git a/src/libraries/System.Linq.AsyncEnumerable/ref/System.Linq.AsyncEnumerable.csproj b/src/libraries/System.Linq.AsyncEnumerable/ref/System.Linq.AsyncEnumerable.csproj
@@ -1,8 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.0;netstandard2.1;$(NetFrameworkMinimum)</TargetFrameworks>
   </PropertyGroup>
-  
+
   <ItemGroup>
     <Compile Include="System.Linq.AsyncEnumerable.cs" />
   </ItemGroup>
@@ -16,13 +16,16 @@
     <Compile Include="$(CoreLibSharedDir)System\Runtime\CompilerServices\OverloadResolutionPriorityAttribute.cs" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
+    <PackageReference Include="System.ValueTuple" Version="$(SystemValueTupleVersion)" />
     <PackageReference Include="System.Threading.Tasks.Extensions" Version="$(SystemThreadingTasksExtensionsVersion)" />
     <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Bcl.AsyncInterfaces\src\Microsoft.Bcl.AsyncInterfaces.csproj" />
     <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Bcl.Memory\src\Microsoft.Bcl.Memory.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
-    <PackageReference Include="System.ValueTuple" Version="$(SystemValueTupleVersion)" />
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+    <PackageReference Include="System.Threading.Tasks.Extensions" Version="$(SystemThreadingTasksExtensionsVersion)" />
+    <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Bcl.AsyncInterfaces\src\Microsoft.Bcl.AsyncInterfaces.csproj" />
+    <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Bcl.Memory\src\Microsoft.Bcl.Memory.csproj" />
   </ItemGroup>
-</Project>
+</Project>
-Original file line number
+Diff line change
@@ Expand Up / @@ -44,7 +44,7 @@ internal void Add(SerializationRecord record) @@
                 }
                 else
                 {
-    #if NET
+    #if !NETFRAMEWORK && !NETSTANDARD2_0
                     if (_map.TryAdd(record.Id, record))
                     {
                         return;
@@ Expand Down @@