diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index 8d15853b82f75..51b54016b1366 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -360,17 +360,17 @@
       <Uri>https://github.com/dotnet/runtime-assets</Uri>
       <Sha>f282faa0ddd1b3672a3cba54518943fb1d0b4e36</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.Net.Compilers.Toolset" Version="4.10.0-2.24114.13">
+    <Dependency Name="Microsoft.Net.Compilers.Toolset" Version="4.10.0-3.24202.15">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>77372c66fd54927312b5b0a2e399e192f74445c9</Sha>
+      <Sha>cbca41cad4e21c29548e9e57d7135740b6f78df9</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis" Version="4.10.0-2.24114.13">
+    <Dependency Name="Microsoft.CodeAnalysis" Version="4.10.0-3.24202.15">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>77372c66fd54927312b5b0a2e399e192f74445c9</Sha>
+      <Sha>cbca41cad4e21c29548e9e57d7135740b6f78df9</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.CSharp" Version="4.10.0-2.24114.13">
+    <Dependency Name="Microsoft.CodeAnalysis.CSharp" Version="4.10.0-3.24202.15">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>77372c66fd54927312b5b0a2e399e192f74445c9</Sha>
+      <Sha>cbca41cad4e21c29548e9e57d7135740b6f78df9</Sha>
     </Dependency>
     <Dependency Name="Microsoft.CodeAnalysis.Analyzers" Version="3.11.0-beta1.24177.1">
       <Uri>https://github.com/dotnet/roslyn-analyzers</Uri>
@@ -381,9 +381,9 @@
       <Sha>ad732e236e7ffcb66de4b45a1b736aad4ccdcd83</Sha>
     </Dependency>
     <!-- Intermediate is necessary for source build. -->
-    <Dependency Name="Microsoft.SourceBuild.Intermediate.roslyn" Version="4.10.0-2.24114.13">
+    <Dependency Name="Microsoft.SourceBuild.Intermediate.roslyn" Version="4.10.0-3.24202.15">
       <Uri>https://github.com/dotnet/roslyn</Uri>
-      <Sha>77372c66fd54927312b5b0a2e399e192f74445c9</Sha>
+      <Sha>cbca41cad4e21c29548e9e57d7135740b6f78df9</Sha>
       <SourceBuild RepoName="roslyn" ManagedOnly="true" />
     </Dependency>
     <Dependency Name="Microsoft.DotNet.ApiCompat.Task" Version="9.0.100-preview.4.24175.4">
diff --git a/eng/Versions.props b/eng/Versions.props
index acc78b3a7b26b..67ef014c3a777 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -42,9 +42,9 @@
       Any tools that contribute to the design-time experience should use the MicrosoftCodeAnalysisVersion_LatestVS property above to ensure
       they do not break the local dev experience.
     -->
-    <MicrosoftCodeAnalysisCSharpVersion>4.10.0-2.24114.13</MicrosoftCodeAnalysisCSharpVersion>
-    <MicrosoftCodeAnalysisVersion>4.10.0-2.24114.13</MicrosoftCodeAnalysisVersion>
-    <MicrosoftNetCompilersToolsetVersion>4.10.0-2.24114.13</MicrosoftNetCompilersToolsetVersion>
+    <MicrosoftCodeAnalysisCSharpVersion>4.10.0-3.24202.15</MicrosoftCodeAnalysisCSharpVersion>
+    <MicrosoftCodeAnalysisVersion>4.10.0-3.24202.15</MicrosoftCodeAnalysisVersion>
+    <MicrosoftNetCompilersToolsetVersion>4.10.0-3.24202.15</MicrosoftNetCompilersToolsetVersion>
   </PropertyGroup>
   <!--
     For source generator support we need to target multiple versions of Roslyn in order to be able to run on older versions of Roslyn.
diff --git a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Condition.cs b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Condition.cs
index 1c6cdadaf0227..ba8aba61a0a1b 100644
--- a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Condition.cs
+++ b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Condition.cs
@@ -89,7 +89,9 @@ private unsafe void RemoveWaiter(Waiter waiter)
 
         public Condition(Lock @lock)
         {
+#pragma warning disable CS9216 // A value of type 'System.Threading.Lock' converted to a different type will use likely unintended monitor-based locking in 'lock' statement.
             ArgumentNullException.ThrowIfNull(@lock);
+#pragma warning restore CS9216
             _lock = @lock;
         }
 
diff --git a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/SyncTable.cs b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/SyncTable.cs
index c75a5fe9de40d..c9ec4990f5907 100644
--- a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/SyncTable.cs
+++ b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/SyncTable.cs
@@ -140,7 +140,7 @@ public static unsafe int AssignEntry(object obj, int* pHeader)
 
                     // Found a free entry to assign
                     Debug.Assert(!entry.Owner.IsAllocated);
-                    Debug.Assert(entry.Lock == null);
+                    Debug.Assert(entry.Lock is null);
                     Debug.Assert(entry.HashCode == 0);
 
                     // Set up the new entry.  We should not fail after this point.
diff --git a/src/libraries/Microsoft.CSharp/tests/BindingErrors.cs b/src/libraries/Microsoft.CSharp/tests/BindingErrors.cs
index cec23a2f0cb36..d5cf0644cebe1 100644
--- a/src/libraries/Microsoft.CSharp/tests/BindingErrors.cs
+++ b/src/libraries/Microsoft.CSharp/tests/BindingErrors.cs
@@ -61,6 +61,10 @@ public void DoSomething(double d)
             {
             }
 
+            public void DoSomething(float d)
+            {
+            }
+
             public static void DoSomething(int i)
             {
             }
diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/NativeRuntimeEventSource.Threading.NativeSinks.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/NativeRuntimeEventSource.Threading.NativeSinks.cs
index 432540c79ff15..d1609f8775e12 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/NativeRuntimeEventSource.Threading.NativeSinks.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/NativeRuntimeEventSource.Threading.NativeSinks.cs
@@ -94,7 +94,12 @@ private void ContentionLockCreated(nint LockID, nint AssociatedObjectID, ushort
 
         [NonEvent]
         [MethodImpl(MethodImplOptions.NoInlining)]
-        public void ContentionLockCreated(Lock lockObj) => ContentionLockCreated(lockObj.LockIdForEvents, ObjectIDForEvents(lockObj));
+        public void ContentionLockCreated(Lock lockObj) =>
+            ContentionLockCreated(
+                lockObj.LockIdForEvents,
+#pragma warning disable CS9216 // A value of type 'System.Threading.Lock' converted to a different type will use likely unintended monitor-based locking in 'lock' statement.
+                ObjectIDForEvents(lockObj));
+#pragma warning restore CS9216
 
         [Event(81, Level = EventLevel.Informational, Message = Messages.ContentionStart, Task = Tasks.Contention, Opcode = EventOpcode.Start, Version = 2, Keywords = Keywords.ContentionKeyword)]
         private void ContentionStart(
@@ -115,7 +120,9 @@ public void ContentionStart(Lock lockObj) =>
                 ContentionFlagsMap.Managed,
                 DefaultClrInstanceId,
                 lockObj.LockIdForEvents,
+#pragma warning disable CS9216 // A value of type 'System.Threading.Lock' converted to a different type will use likely unintended monitor-based locking in 'lock' statement.
                 ObjectIDForEvents(lockObj),
+#pragma warning restore CS9216
                 lockObj.OwningThreadId);
 
         [Event(91, Level = EventLevel.Informational, Message = Messages.ContentionStop, Task = Tasks.Contention, Opcode = EventOpcode.Stop, Version = 1, Keywords = Keywords.ContentionKeyword)]
diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/NativeRuntimeEventSource.Threading.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/NativeRuntimeEventSource.Threading.cs
index 8c85770e1f0aa..6dcb332112dc5 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/NativeRuntimeEventSource.Threading.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/NativeRuntimeEventSource.Threading.cs
@@ -107,7 +107,12 @@ private unsafe void ContentionLockCreated(nint LockID, nint AssociatedObjectID,
 
         [NonEvent]
         [MethodImpl(MethodImplOptions.NoInlining)]
-        public void ContentionLockCreated(Lock lockObj) => ContentionLockCreated(lockObj.LockIdForEvents, ObjectIDForEvents(lockObj));
+        public void ContentionLockCreated(Lock lockObj) =>
+            ContentionLockCreated(
+                lockObj.LockIdForEvents,
+#pragma warning disable CS9216 // A value of type 'System.Threading.Lock' converted to a different type will use likely unintended monitor-based locking in 'lock' statement.
+                ObjectIDForEvents(lockObj));
+#pragma warning restore CS9216
 
         [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:UnrecognizedReflectionPattern", Justification = "Parameters to this method are primitive and are trimmer safe")]
         [Event(81, Level = EventLevel.Informational, Message = Messages.ContentionStart, Task = Tasks.Contention, Opcode = EventOpcode.Start, Version = 2, Keywords = Keywords.ContentionKeyword)]
@@ -146,7 +151,9 @@ public void ContentionStart(Lock lockObj) =>
                 ContentionFlagsMap.Managed,
                 DefaultClrInstanceId,
                 lockObj.LockIdForEvents,
+#pragma warning disable CS9216 // A value of type 'System.Threading.Lock' converted to a different type will use likely unintended monitor-based locking in 'lock' statement.
                 ObjectIDForEvents(lockObj),
+#pragma warning restore CS9216
                 lockObj.OwningThreadId);
 
         [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:UnrecognizedReflectionPattern", Justification = "Parameters to this method are primitive and are trimmer safe")]
diff --git a/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs b/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs
index f9f34ecb19cf0..b7961869eac5d 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs
@@ -130,7 +130,7 @@ internal Scope(Lock lockObj, ThreadId currentThreadId)
             public void Dispose()
             {
                 Lock? lockObj = _lockObj;
-                if (lockObj != null)
+                if (lockObj is not null)
                 {
                     _lockObj = null;
                     lockObj.Exit(_currentThreadId);
diff --git a/src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/CompileFails.cs b/src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/CompileFails.cs
index a4fad790817cb..7586edccb3647 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/CompileFails.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/CompileFails.cs
@@ -41,7 +41,7 @@ public static IEnumerable<object[]> ComInterfaceGeneratorSnippetsToCompile()
             } };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(ComInterfaceGeneratorSnippetsToCompile))]
         public async Task ValidateComInterfaceGeneratorSnippets(string id, string source, DiagnosticResult[] expectedDiagnostics)
         {
@@ -335,7 +335,7 @@ public static IEnumerable<object[]> InvalidManagedToUnmanagedCodeSnippetsToCompi
             yield return new[] { ID(), customStructMarshallingCodeSnippets.Stateful.ByValueOutParameter };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(InvalidUnmanagedToManagedCodeSnippetsToCompile), GeneratorKind.ComInterfaceGenerator)]
         public async Task ValidateInvalidUnmanagedToManagedCodeSnippets(string id, string source, DiagnosticResult[] expectedDiagnostics)
         {
@@ -349,7 +349,7 @@ public async Task ValidateInvalidUnmanagedToManagedCodeSnippets(string id, strin
             await test.RunAsync();
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(InvalidManagedToUnmanagedCodeSnippetsToCompile), GeneratorKind.ComInterfaceGenerator)]
         public async Task ValidateInvalidManagedToUnmanagedCodeSnippets(string id, string source)
         {
@@ -361,7 +361,7 @@ public async Task ValidateInvalidManagedToUnmanagedCodeSnippets(string id, strin
             await VerifyComInterfaceGenerator.VerifySourceGeneratorAsync(source, expectedDiagnostic);
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(StringMarshallingCodeSnippets), GeneratorKind.ComInterfaceGenerator)]
         public async Task ValidateStringMarshallingDiagnostics(string id, string source, DiagnosticResult[] expectedDiagnostics)
         {
@@ -512,7 +512,7 @@ public static unsafe partial class Test {
             }
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(StringMarshallingCustomTypeVisibilities))]
         public async Task VerifyStringMarshallingCustomTypeWithLessVisibilityThanInterfaceWarns(string id, string source, DiagnosticResult[] diagnostics)
         {
@@ -520,7 +520,7 @@ public async Task VerifyStringMarshallingCustomTypeWithLessVisibilityThanInterfa
             await VerifyComInterfaceGenerator.VerifySourceGeneratorAsync(source, diagnostics);
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(InterfaceVisibilities))]
         public async Task VerifyInterfaceWithLessVisibilityThanInterfaceWarns(string id, string source, DiagnosticResult[] diagnostics)
         {
@@ -772,7 +772,7 @@ string Source(
             }
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CountParameterIsOutSnippets))]
         public async Task ValidateSizeParameterRefKindDiagnostics(string ID, string source, params DiagnosticResult[] diagnostics)
         {
@@ -889,7 +889,7 @@ partial interface I
             }
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(IntAndEnumReturnTypeSnippets))]
         public async Task ValidateReturnTypeInfoDiagnostics(string id, string source, DiagnosticResult[] diagnostics)
         {
diff --git a/src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/Compiles.cs b/src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/Compiles.cs
index 421e989f870ba..feb69cc01da9c 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/Compiles.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/Compiles.cs
@@ -320,7 +320,7 @@ public static IEnumerable<object[]> CustomCollectionsManagedToUnmanaged(Generato
             yield return new[] { ID(), customCollectionMarshallingCodeSnippetsManagedToUnmanaged.Stateful.NonBlittableElementNativeToManagedOnlyReturnValue };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToCompile), GeneratorKind.VTableIndexStubGenerator)]
         [MemberData(nameof(ManagedToUnmanagedCodeSnippetsToCompile), GeneratorKind.VTableIndexStubGenerator)]
         [MemberData(nameof(UnmanagedToManagedCodeSnippetsToCompile), GeneratorKind.VTableIndexStubGenerator)]
@@ -348,7 +348,7 @@ public static IEnumerable<object[]> ManagedToUnmanagedComInterfaceSnippetsToComp
             yield return new[] { ID(), codeSnippets.MarshalAsParameterAndModifiers("object", System.Runtime.InteropServices.UnmanagedType.Struct) };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToCompile), GeneratorKind.ComInterfaceGenerator)]
         [MemberData(nameof(CustomCollections), GeneratorKind.ComInterfaceGenerator)]
         [MemberData(nameof(ManagedToUnmanagedCodeSnippetsToCompile), GeneratorKind.ComInterfaceGeneratorComObjectWrapper)]
diff --git a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CompileFails.cs b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CompileFails.cs
index 676cd56e2e6a6..ecbe1c3d19e02 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CompileFails.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CompileFails.cs
@@ -785,7 +785,7 @@ public static IEnumerable<object[]> CodeSnippetsToCompile()
             } };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToCompile))]
         public async Task ValidateSnippets(string id, string source, DiagnosticResult[] diagnostics)
         {
@@ -804,7 +804,7 @@ public static IEnumerable<object[]> CodeSnippetsToCompile_InvalidCode()
             yield return new[] { ID(), CodeSnippets.IncorrectAttributeFieldType };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToCompile_InvalidCode))]
         public async Task ValidateSnippets_InvalidCodeGracefulFailure(string id, string source)
         {
diff --git a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/Compiles.cs b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/Compiles.cs
index b78fbc8552f2a..4c80ac61cc460 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/Compiles.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/Compiles.cs
@@ -440,7 +440,7 @@ public static IEnumerable<object[]> CustomCollections()
             yield return new[] { ID(), CodeSnippets.CollectionsOfCollectionsStress };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToCompile))]
         [MemberData(nameof(CustomCollections))]
         public async Task ValidateSnippets(string id, string source)
@@ -461,7 +461,7 @@ public static IEnumerable<object[]> CodeSnippetsToCompileWithPreprocessorSymbols
             yield return new object[] { ID(), CodeSnippets.PreprocessorIfAfterAttributeAroundFunctionAdditionalFunctionAfter("Foo"), new string[] { "Foo" } };
             yield return new object[] { ID(), CodeSnippets.PreprocessorIfAfterAttributeAroundFunctionAdditionalFunctionAfter("Foo"), Array.Empty<string>() };
         }
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToCompileWithPreprocessorSymbols))]
         public async Task ValidateSnippetsWithPreprocessorDefinitions(string id, string source, IEnumerable<string> preprocessorSymbols)
         {
@@ -530,7 +530,7 @@ public static IEnumerable<object[]> CodeSnippetsToValidateFallbackForwarder()
             }
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToValidateFallbackForwarder))]
         [OuterLoop("Uses the network for downlevel ref packs")]
         public async Task ValidateSnippetsFallbackForwarder(string id, string source, TestTargetFramework targetFramework, bool expectFallbackForwarder)
@@ -576,7 +576,7 @@ public static IEnumerable<object[]> FullyBlittableSnippetsToCompile()
             yield return new[] { ID(), CodeSnippets.BasicParameterByValue("int") };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(FullyBlittableSnippetsToCompile))]
         public async Task ValidateSnippetsWithBlittableAutoForwarding(string id, string source)
         {
@@ -616,7 +616,7 @@ public static IEnumerable<object[]> SnippetsWithBlittableTypesButNonBlittableDat
             yield return new[] { ID(), CodeSnippets.SetLastErrorTrue<int>() };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(SnippetsWithBlittableTypesButNonBlittableDataToCompile))]
         public async Task ValidateSnippetsWithBlittableTypesButNonBlittableMetadataDoNotAutoForward(string id, string source)
         {
@@ -689,7 +689,7 @@ public static IEnumerable<object[]> CodeSnippetsToCompileMultipleSources()
             yield return new object[] { ID(), new[] { CodeSnippets.BasicParameterByValue("int[]", CodeSnippets.DisableRuntimeMarshalling), CodeSnippets.BasicParameterWithByRefModifier("ref", "int") } };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToCompileMultipleSources))]
         public async Task ValidateSnippetsWithMultipleSources(string id, string[] sources)
         {
@@ -717,7 +717,7 @@ public class Basic { }
             yield return new object[] { ID(), source, TestTargetFramework.Net };
         }
 
-        [ParallelTheory]
+        [Theory]
         [MemberData(nameof(CodeSnippetsToVerifyNoTreesProduced))]
         public async Task ValidateNoGeneratedOuptutForNoImport(string id, string source, TestTargetFramework framework)
         {
diff --git a/src/libraries/System.Runtime/tests/System.Dynamic.Runtime.Tests/Dynamic.Context/Conformance.dynamic.context.operator.regclass.cs b/src/libraries/System.Runtime/tests/System.Dynamic.Runtime.Tests/Dynamic.Context/Conformance.dynamic.context.operator.regclass.cs
index 789077324c421..c5af627116a44 100644
--- a/src/libraries/System.Runtime/tests/System.Dynamic.Runtime.Tests/Dynamic.Context/Conformance.dynamic.context.operator.regclass.cs
+++ b/src/libraries/System.Runtime/tests/System.Dynamic.Runtime.Tests/Dynamic.Context/Conformance.dynamic.context.operator.regclass.cs
@@ -4426,6 +4426,10 @@ public static void Foo(string x)
         {
         }
 
+        public static void Foo(int x)
+        {
+        }
+
         public void Foo2()
         {
         }
diff --git a/src/libraries/System.Runtime/tests/System.Dynamic.Runtime.Tests/Dynamic.Declarations/Conformance.dynamic.declarations.returnType.indexers.cs b/src/libraries/System.Runtime/tests/System.Dynamic.Runtime.Tests/Dynamic.Declarations/Conformance.dynamic.declarations.returnType.indexers.cs
index 131cbebf009ed..e8f7e2f9869fd 100644
--- a/src/libraries/System.Runtime/tests/System.Dynamic.Runtime.Tests/Dynamic.Declarations/Conformance.dynamic.declarations.returnType.indexers.cs
+++ b/src/libraries/System.Runtime/tests/System.Dynamic.Runtime.Tests/Dynamic.Declarations/Conformance.dynamic.declarations.returnType.indexers.cs
@@ -262,6 +262,14 @@ public class MyClass
                     return d;
                 }
             }
+            public dynamic this[long x, dynamic d]
+            {
+                get
+                {
+                    MyClass.Status = 2;
+                    return d;
+                }
+            }
         }
 
         [Fact]
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/AttRegexTests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/AttRegexTests.cs
index 829432b466302..8bc7092292300 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/AttRegexTests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/AttRegexTests.cs
@@ -45,7 +45,7 @@ public static IEnumerable<object[]> Test_MemberData()
             foreach (RegexEngine engine in RegexHelpers.AvailableEngines)
             {
                 (RegexOptions Options, string Pattern, string Input, string Expected)[] cases = Match_MemberData_Cases(engine).ToArray();
-                Regex[] regexes = RegexHelpers.GetRegexesAsync(engine, cases.Select(c => (c.Pattern, (CultureInfo?)null, (RegexOptions?)c.Options, (TimeSpan?)null)).ToArray()).Result;
+                Regex[] regexes = RegexHelpers.GetRegexes(engine, cases.Select(c => (c.Pattern, (CultureInfo?)null, (RegexOptions?)c.Options, (TimeSpan?)null)).ToArray());
                 for (int i = 0; i < regexes.Length; i++)
                 {
                     yield return new object[] { regexes[i], cases[i].Input, cases[i].Expected };
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/MonoRegexTests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/MonoRegexTests.cs
index 8aef06bae0cb2..8865d17e05c9c 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/MonoRegexTests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/MonoRegexTests.cs
@@ -55,7 +55,7 @@ public static IEnumerable<object[]> ValidateRegex_MemberData()
             {
                 (string Pattern, RegexOptions Options, string Input, string Expected)[] allEngineCases = Cases(engine).ToArray();
 
-                Regex[] results = RegexHelpers.GetRegexesAsync(engine, allEngineCases.Select(c => (c.Pattern, (CultureInfo?)null, (RegexOptions?)c.Options, (TimeSpan?)null)).ToArray()).Result;
+                Regex[] results = RegexHelpers.GetRegexes(engine, allEngineCases.Select(c => (c.Pattern, (CultureInfo?)null, (RegexOptions?)c.Options, (TimeSpan?)null)).ToArray());
                 for (int i = 0; i < results.Length; i++)
                 {
                     string expected = allEngineCases[i].Expected;
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Groups.Tests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Groups.Tests.cs
index c3ff5b595caa2..42456389f9906 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Groups.Tests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Groups.Tests.cs
@@ -16,7 +16,7 @@ public static IEnumerable<object[]> Groups_MemberData()
             foreach (RegexEngine engine in RegexHelpers.AvailableEngines)
             {
                 (CultureInfo Culture, string Pattern, string Input, RegexOptions Options, string[] Expected)[] cases = Groups_MemberData_Cases(engine).ToArray();
-                Regex[] regexes = RegexHelpers.GetRegexesAsync(engine, cases.Select(c => (c.Pattern, c.Culture, (RegexOptions?)c.Options, (TimeSpan?)null)).ToArray()).Result;
+                Regex[] regexes = RegexHelpers.GetRegexes(engine, cases.Select(c => (c.Pattern, c.Culture, (RegexOptions?)c.Options, (TimeSpan?)null)).ToArray());
                 for (int i = 0; i < regexes.Length; i++)
                 {
                     yield return new object[] { regexes[i], cases[i].Culture, cases[i].Input, cases[i].Expected };
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.KnownPattern.Tests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.KnownPattern.Tests.cs
index b34ede47dd2ef..5748fd8df3c2e 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.KnownPattern.Tests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.KnownPattern.Tests.cs
@@ -1553,12 +1553,12 @@ public async Task PatternsDataSet_ConstructRegexForAll_NonBacktracking()
         [OuterLoop("Takes minutes to generate and compile thousands of expressions")]
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess), nameof(PlatformDetection.IsNotMobile), nameof(PlatformDetection.IsNotBrowser))] // consumes a lot of memory, doesn't work on mobile
         [ActiveIssue("https://github.com/dotnet/runtime/issues/80018", TestRuntimes.Mono)]
-        public void PatternsDataSet_ConstructRegexForAll_SourceGenerated()
+        public async Task PatternsDataSet_ConstructRegexForAll_SourceGenerated()
         {
-            Parallel.ForEach(s_patternsDataSet.Value.Chunk(50), chunk =>
+            await Parallel.ForEachAsync(s_patternsDataSet.Value.Chunk(50), async (chunk, ct) =>
             {
-                RegexHelpers.GetRegexesAsync(RegexEngine.SourceGenerated,
-                    chunk.Select(r => (r.Pattern, (CultureInfo?)null, (RegexOptions?)r.Options, (TimeSpan?)null)).ToArray()).GetAwaiter().GetResult();
+                await RegexHelpers.GetRegexesAsync(RegexEngine.SourceGenerated,
+                    chunk.Select(r => (r.Pattern, (CultureInfo?)null, (RegexOptions?)r.Options, (TimeSpan?)null)).ToArray());
             });
         }
 
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Match.Tests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Match.Tests.cs
index 2c7b9b0f185e4..1b06272fba64a 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Match.Tests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Match.Tests.cs
@@ -21,7 +21,7 @@ public static IEnumerable<object[]> Match_MemberData()
             foreach (RegexEngine engine in RegexHelpers.AvailableEngines)
             {
                 (string Pattern, string Input, RegexOptions Options, int Beginning, int Length, bool ExpectedSuccess, string ExpectedValue)[] cases = Match_MemberData_Cases(engine).ToArray();
-                Regex[] regexes = RegexHelpers.GetRegexesAsync(engine, cases.Select(c => (c.Pattern, (CultureInfo?)null, (RegexOptions?)c.Options, (TimeSpan?)null)).ToArray()).Result;
+                Regex[] regexes = RegexHelpers.GetRegexes(engine, cases.Select(c => (c.Pattern, (CultureInfo?)null, (RegexOptions?)c.Options, (TimeSpan?)null)).ToArray());
                 for (int i = 0; i < regexes.Length; i++)
                 {
                     yield return new object[] { engine, cases[i].Pattern, cases[i].Input, cases[i].Options, regexes[i], cases[i].Beginning, cases[i].Length, cases[i].ExpectedSuccess, cases[i].ExpectedValue };
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Tests.Common.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Tests.Common.cs
index bb0b4b8f39d4b..4d4f2252839ae 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Tests.Common.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Tests.Common.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Linq;
@@ -123,6 +124,22 @@ public static async Task<Regex> GetRegexAsync(RegexEngine engine, [StringSyntax(
                 new Regex(pattern, options.Value | OptionsFromEngine(engine), matchTimeout.Value);
         }
 
+        public static Regex[] GetRegexes(RegexEngine engine, params (string pattern, CultureInfo? culture, RegexOptions? options, TimeSpan? matchTimeout)[] regexes)
+        {
+            if (engine == RegexEngine.SourceGenerated)
+            {
+                // Source generated regex creation can complete asynchronously, which is why GetRegexesAsync is async.
+                // xunit theory member data in xunit v2 may only be synchronous, and Roslyn's APIs are only asynchronous.
+                // As such, they need to block to get the results. But if they block on xunit's limited synchronization
+                // scheduler, they could deadlock, so escape the context by queueing the work to a thread pool thread.
+                return Task.Run(() => GetRegexesAsync(engine, regexes)).GetAwaiter().GetResult();
+            }
+
+            Task<Regex[]> t = GetRegexesAsync(engine, regexes);
+            Debug.Assert(t.IsCompleted);
+            return t.GetAwaiter().GetResult();
+        }
+
         public static async Task<Regex[]> GetRegexesAsync(RegexEngine engine, params (string pattern, CultureInfo? culture, RegexOptions? options, TimeSpan? matchTimeout)[] regexes)
         {
             if (engine == RegexEngine.SourceGenerated)
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexPcreTests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexPcreTests.cs
index 0063cf802fdf1..d522ab3bc2ab6 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexPcreTests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexPcreTests.cs
@@ -19,7 +19,7 @@ public static IEnumerable<object[]> PcreTestData()
             foreach (RegexEngine engine in RegexHelpers.AvailableEngines)
             {
                 (string pattern, RegexOptions options, string input, bool expectedSuccess)[] cases = PcreTestData_Cases(engine).ToArray();
-                Regex[] regexes = RegexHelpers.GetRegexesAsync(engine, cases.Select(c => (c.pattern, (CultureInfo?)null, (RegexOptions?)c.options, (TimeSpan?)null)).ToArray()).Result;
+                Regex[] regexes = RegexHelpers.GetRegexes(engine, cases.Select(c => (c.pattern, (CultureInfo?)null, (RegexOptions?)c.options, (TimeSpan?)null)).ToArray());
                 for (int i = 0; i < regexes.Length; i++)
                 {
                     yield return new object[] { regexes[i], cases[i].input, cases[i].expectedSuccess };
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexRustTests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexRustTests.cs
index 1a6a807a57cfb..be000266052fc 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexRustTests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexRustTests.cs
@@ -18,7 +18,7 @@ public static IEnumerable<object[]> MatchStartAndEndPositions_MemberData()
             foreach (RegexEngine engine in RegexHelpers.AvailableEngines)
             {
                 (string Pattern, string Input, IEnumerable<(int, int)> MatchBoundaries)[] cases = MatchStartAndEndPositions_MemberData_Cases().ToArray();
-                Regex[] regexes = RegexHelpers.GetRegexesAsync(engine, cases.Select(c => (c.Pattern, (CultureInfo?)null, (RegexOptions?)RegexOptions.None, (TimeSpan?)null)).ToArray()).Result;
+                Regex[] regexes = RegexHelpers.GetRegexes(engine, cases.Select(c => (c.Pattern, (CultureInfo?)null, (RegexOptions?)RegexOptions.None, (TimeSpan?)null)).ToArray());
                 for (int i = 0; i < regexes.Length; i++)
                 {
                     yield return new object[] { regexes[i], cases[i].Input, cases[i].MatchBoundaries };
diff --git a/src/tools/illink/test/Mono.Linker.Tests.Cases/DataFlow/DynamicObjects.cs b/src/tools/illink/test/Mono.Linker.Tests.Cases/DataFlow/DynamicObjects.cs
index a9f8f00296b5c..d048bec91e5d2 100644
--- a/src/tools/illink/test/Mono.Linker.Tests.Cases/DataFlow/DynamicObjects.cs
+++ b/src/tools/illink/test/Mono.Linker.Tests.Cases/DataFlow/DynamicObjects.cs
@@ -54,26 +54,27 @@ static void MethodWithDynamicParameter (dynamic arg)
 				arg.MethodWithDynamicParameter (arg);
 			}
 
-			[ExpectedWarning ("IL2026", "Microsoft.CSharp.RuntimeBinder.Binder.InvokeConstructor")]
-			[ExpectedWarning ("IL3050", ProducedBy = Tool.NativeAot)] // https://github.com/dotnet/runtime/issues/94427
-			static void ObjectCreationDynamicArgument ()
-			{
-				dynamic dynamicObject = "Some string";
-				var x = new ClassWithDynamicCtor (dynamicObject);
-			}
-
-			class ClassWithDynamicCtor
-			{
-				public ClassWithDynamicCtor (dynamic arg)
-				{
-				}
-			}
+			// Roslyn codegen no longer produces a call to Binder.InvokeConstructor.
+			// [ExpectedWarning ("IL2026", "Microsoft.CSharp.RuntimeBinder.Binder.InvokeConstructor")]
+			// [ExpectedWarning ("IL3050", ProducedBy = Tool.NativeAot)] // https://github.com/dotnet/runtime/issues/94427
+			// static void ObjectCreationDynamicArgument ()
+			// {
+			// 	dynamic dynamicObject = "Some string";
+			// 	var x = new ClassWithDynamicCtor (dynamicObject);
+			// }
+
+			// class ClassWithDynamicCtor
+			// {
+			// 	public ClassWithDynamicCtor (dynamic arg)
+			// 	{
+			// 	}
+			// }
 
 			public static void Test ()
 			{
 				DynamicArgument ();
 				DynamicParameter ();
-				ObjectCreationDynamicArgument ();
+				// ObjectCreationDynamicArgument ();
 			}
 		}