dotnet · Evangelink · Jun 25, 2026 · Jun 24, 2026 · Jun 24, 2026 · Jun 25, 2026
diff --git a/test/EndToEnd.Tests/EndToEnd.Tests.csproj b/test/EndToEnd.Tests/EndToEnd.Tests.csproj
@@ -5,8 +5,8 @@
 
   <PropertyGroup>
     <TargetFramework>$(SdkTargetFramework)</TargetFramework>
-    <!-- These tests rely on global process state, so run serially ([assembly: DoNotParallelize]). -->
-    <MSTestParallelizeScope></MSTestParallelizeScope>
+    <!-- These tests rely on global process state, so run serially. None makes MSTest.Sdk emit [assembly: DoNotParallelize]. -->
+    <MSTestParallelizeScope>None</MSTestParallelizeScope>
   </PropertyGroup>
 
   <ItemGroup>

diff --git a/test/EndToEnd.Tests/GivenDotNetUsesMSBuild.cs b/test/EndToEnd.Tests/GivenDotNetUsesMSBuild.cs
@@ -3,8 +3,6 @@
 
 #nullable disable
 
-[assembly: DoNotParallelize]
-
 namespace EndToEnd.Tests
 {
     [TestClass]

diff --git a/test/Microsoft.DotNet.Cli.Utils.Tests/DependencyProviderTests.cs b/test/Microsoft.DotNet.Cli.Utils.Tests/DependencyProviderTests.cs
@@ -8,11 +8,6 @@
 namespace Microsoft.DotNet.Cli.Utils.Tests
 {
 #pragma warning disable CA1416
-    // These tests share a single hardcoded registry key (.NET_SDK_TEST_PROVIDER_KEY) and mutate it
-    // (create/add/remove/delete), so they must not run concurrently. xUnit ran methods within a class
-    // serially; under MSTest MethodLevel parallelism (see https://github.com/dotnet/sdk/pull/54766)
-    // they race, producing intermittent "expected 1, actual 2 dependents" and missing-subkey failures.
-    [DoNotParallelize]
     [TestClass]
     public class DependencyProviderTests
     {

diff --git a/test/Microsoft.DotNet.MSBuildSdkResolver.Tests/GivenAnMSBuildSdkResolver.cs b/test/Microsoft.DotNet.MSBuildSdkResolver.Tests/GivenAnMSBuildSdkResolver.cs
@@ -7,8 +7,6 @@
 using Microsoft.DotNet.DotNetSdkResolver;
 using Microsoft.DotNet.MSBuildSdkResolver;
 
-[assembly: DoNotParallelize]
-
 namespace Microsoft.DotNet.Cli.Utils.Tests
 {
     [TestClass]

diff --git a/...icrosoft.DotNet.MSBuildSdkResolver.Tests/Microsoft.DotNet.MSBuildSdkResolver.Tests.csproj b/...icrosoft.DotNet.MSBuildSdkResolver.Tests/Microsoft.DotNet.MSBuildSdkResolver.Tests.csproj
@@ -7,9 +7,6 @@
 
   <PropertyGroup>
     <TargetFramework>net472</TargetFramework>
-    <!-- This project's tests rely on global process state, so disable parallelization
-         (the repo default is MethodLevel). [assembly: DoNotParallelize] enforces serial execution. -->
-    <MSTestParallelizeScope></MSTestParallelizeScope>
     <!-- For product build, the .NET Framework TFM only builds in the second build pass as it depends on assets from other
          verticals that are built in the first build pass.
          Disabling this project as references are not building in this case. -->

diff --git a/test/Microsoft.DotNet.PackageInstall.Tests/EndToEndToolTests.cs b/test/Microsoft.DotNet.PackageInstall.Tests/EndToEndToolTests.cs
@@ -8,7 +8,6 @@
 
 namespace Microsoft.DotNet.PackageInstall.Tests
 {
-    [DoNotParallelize]
     [TestClass]
     public class EndToEndToolTests : SdkTest
     {

diff --git a/test/Microsoft.DotNet.PackageInstall.Tests/ToolPackageDownloaderTests.cs b/test/Microsoft.DotNet.PackageInstall.Tests/ToolPackageDownloaderTests.cs
@@ -34,7 +34,6 @@ public DotnetEnvironmentTestFixture()
         public void Dispose() => Environment.SetEnvironmentVariable(_PATH_VAR_NAME, _originalPath);
     }
 
-    [DoNotParallelize]
     [TestClass]
     public class ToolPackageDownloaderTests : SdkTest
     {

diff --git a/test/Microsoft.DotNet.PackageInstall.Tests/ToolPackageInstallerNugetCacheTests.cs b/test/Microsoft.DotNet.PackageInstall.Tests/ToolPackageInstallerNugetCacheTests.cs
@@ -14,7 +14,6 @@
 
 namespace Microsoft.DotNet.PackageInstall.Tests
 {
-    [DoNotParallelize]
     [TestClass]
     public class ToolPackageInstallToManagedLocationInstaller : SdkTest
     {

diff --git a/test/Microsoft.DotNet.PackageInstall.Tests/ToolPackageUninstallerTests.cs b/test/Microsoft.DotNet.PackageInstall.Tests/ToolPackageUninstallerTests.cs
@@ -15,7 +15,6 @@
 
 namespace Microsoft.DotNet.PackageInstall.Tests
 {
-    [DoNotParallelize]
     [TestClass]
     public class ToolPackageUninstallerTests : SdkTest
     {

@@ -10,11 +10,6 @@
 namespace Microsoft.NET.Build.Containers.UnitTests
 {
     [TestClass]
-    // These tests mutate process-global environment variables (REGISTRY_AUTH_FILE and the
-    // registry credential vars) and rely on AuthHandshakeMessageHandler's static auth-header
-    // cache keyed by a shared registry name. Under MSTest method-level parallelism (the repo
-    // default) the methods/data rows race on that global state, so run them sequentially.
-    [DoNotParallelize]
     public class AuthHandshakeMessageHandlerTests
     {
         public TestContext TestContext { get; set; } = default!;

diff --git a/...Microsoft.NET.Build.Tasks.Tests/GivenACheckForUnsupportedWinMDReferencesMultiThreading.cs b/...Microsoft.NET.Build.Tasks.Tests/GivenACheckForUnsupportedWinMDReferencesMultiThreading.cs
@@ -5,7 +5,6 @@
 
 namespace Microsoft.NET.Build.Tasks.UnitTests
 {
-    [DoNotParallelize]
     [TestClass]
     public class GivenACheckForUnsupportedWinMDReferencesMultiThreading
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateBundleMultiThreading.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateBundleMultiThreading.cs
@@ -22,7 +22,6 @@ namespace Microsoft.NET.Build.Tasks.UnitTests
     /// location different from the <c>TaskEnvironment.ProjectDirectory</c> so a bug that fell
     /// back to <c>Environment.CurrentDirectory</c> / <c>Path.GetFullPath</c> would surface here.
     /// </summary>
-    [DoNotParallelize]
     [TestClass]
     public class GivenAGenerateBundleMultiThreading : IDisposable
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateClsidMapMultiThreading.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateClsidMapMultiThreading.cs
@@ -6,7 +6,6 @@
 
 namespace Microsoft.NET.Build.Tasks.UnitTests
 {
-    [DoNotParallelize]
     [TestClass]
     public class GivenAGenerateClsidMapMultiThreading
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateDepsFileMultiThreading.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateDepsFileMultiThreading.cs
@@ -12,7 +12,6 @@
 
 namespace Microsoft.NET.Build.Tasks.UnitTests
 {
-    [DoNotParallelize]
     [TestClass]
     public class GivenAGenerateDepsFilePathResolution : IDisposable
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateRuntimeConfigMultiThreading.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateRuntimeConfigMultiThreading.cs
@@ -7,7 +7,6 @@
 
 namespace Microsoft.NET.Build.Tasks.UnitTests
 {
-    [DoNotParallelize]
     [TestClass]
     public class GivenAGenerateRuntimeConfigMultiThreading
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateRuntimeConfigurationFiles.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAGenerateRuntimeConfigurationFiles.cs
@@ -3,7 +3,6 @@
 
 namespace Microsoft.NET.Build.Tasks.UnitTests
 {
-    [DoNotParallelize]
     [TestClass]
     public class GivenAGenerateRuntimeConfigurationFiles
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAGetPackagesToPrune.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAGetPackagesToPrune.cs
@@ -13,7 +13,6 @@ namespace Microsoft.NET.Build.Tasks.UnitTests
     /// the task reads the on-disk data from the right place even when the process
     /// current working directory differs from the project directory.
     /// </summary>
-    [DoNotParallelize]
     [TestClass]
     public class GivenAGetPackagesToPrune
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAPickBestRidMultiThreading.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAPickBestRidMultiThreading.cs
@@ -5,7 +5,6 @@
 
 namespace Microsoft.NET.Build.Tasks.UnitTests
 {
-    [DoNotParallelize]
     [TestClass]
     public class GivenAPickBestRidMultiThreading
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAResolveAppHostsMultiThreading.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAResolveAppHostsMultiThreading.cs
@@ -18,7 +18,6 @@ namespace Microsoft.NET.Build.Tasks.UnitTests
     /// Verifies TaskEnvironment-based path resolution against ProjectDirectory (not process CWD)
     /// and that output metadata preserves the original path form.
     /// </summary>
-    [DoNotParallelize]
     [TestClass]
     public class GivenAResolveAppHostsMultiThreading : IDisposable
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAResolvePackageAssetsMultiThreading.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAResolvePackageAssetsMultiThreading.cs
@@ -6,7 +6,6 @@
 
 namespace Microsoft.NET.Build.Tasks.UnitTests
 {
-    [DoNotParallelize]
     [TestClass]
     public class GivenAResolvePackageAssetsMultiThreading
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAResolvePackageFileConflictsMultiThreading.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAResolvePackageFileConflictsMultiThreading.cs
@@ -7,7 +7,6 @@
 using Microsoft.NET.Build.Tasks.ConflictResolution;
 
 namespace Microsoft.NET.Build.Tasks.UnitTests;
-[DoNotParallelize]
 [TestClass]
 public class GivenAResolvePackageFileConflictsMultiThreading : IDisposable
 {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenAResolveRuntimePackAssetsTask.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenAResolveRuntimePackAssetsTask.cs
@@ -7,7 +7,6 @@
 
 namespace Microsoft.NET.Build.Tasks.UnitTests
 {
-    [DoNotParallelize]
     [TestClass]
     public class GivenAResolveRuntimePackAssetsTask : SdkTest
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenATaskEnvironmentDefault.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenATaskEnvironmentDefault.cs
@@ -19,7 +19,6 @@ namespace Microsoft.NET.Build.Tasks.UnitTests
     /// <see cref="TaskEnvironment"/>. Tasks default to <see cref="TaskEnvironment.Fallback"/>
     /// which uses live process state, equivalent to the legacy single-threaded behavior.
     /// </summary>
-    [DoNotParallelize]
     [TestClass]
     public class GivenATaskEnvironmentDefault
     {

diff --git a/test/Microsoft.NET.Build.Tasks.Tests/GivenTasksUseAbsolutePaths.cs b/test/Microsoft.NET.Build.Tasks.Tests/GivenTasksUseAbsolutePaths.cs
@@ -17,7 +17,6 @@ namespace Microsoft.NET.Build.Tasks.UnitTests;
 /// These tests create files in a "project" directory, then verify task behavior by
 /// passing RELATIVE paths and expecting tasks to resolve them via TaskEnvironment.
 /// </summary>
-[DoNotParallelize]
 [TestClass]
 public class GivenTasksUseAbsolutePaths : IDisposable
 {

diff --git a/test/Microsoft.NET.Sdk.Publish.Tasks.Tests/EnvironmentHelperTests.cs b/test/Microsoft.NET.Sdk.Publish.Tasks.Tests/EnvironmentHelperTests.cs
@@ -6,7 +6,6 @@
 namespace Microsoft.NET.Sdk.Publish.Tasks.Tests
 {
     [TestClass]
-    [DoNotParallelize]
     public class EnvironmentHelperTests
     {
         private const string TelemetryOptout = "DOTNET_CLI_TELEMETRY_OPTOUT";

@@ -11,10 +11,6 @@
 namespace Microsoft.NET.Sdk.Razor.Tool
 {
     [TestClass]
-    // GetPidFilePath_UsesEnvironmentVariablePathIfSpecified mutates the process-wide
-    // DOTNET_BUILD_PIDFILE_DIRECTORY environment variable that GetPidFilePath_ReturnsCorrectDefaultPath
-    // reads, so the methods of this class must not run in parallel with each other.
-    [DoNotParallelize]
     public class ServerCommandTest
     {
         [TestMethod]

@@ -15,7 +15,6 @@
 
 namespace Microsoft.NET.Sdk.StaticWebAssets.Tests;
 
-[DoNotParallelize]
 [TestClass]
 public class ComputeStaticWebAssetsTargetPathsMultiThreadingTest
 {

@@ -9,9 +9,6 @@
 
 namespace Microsoft.AspNetCore.Razor.Tasks;
 
-// This test mutates the process-wide current directory, so it must not run
-// concurrently with other tests under MSTest's method-level parallelization.
-[DoNotParallelize]
 [TestClass]
 public class CollectStaticWebAssetsToCopyMultiThreadingTest
 {

@@ -16,7 +16,6 @@
 
 namespace Microsoft.NET.Sdk.StaticWebAssets.Tests;
 
-[DoNotParallelize]
 [TestClass]
 
 public class ComputeEndpointsForReferenceStaticWebAssetsMultiThreadingTest

@@ -437,7 +437,6 @@ public void PreservesAssetGroupsOnFrameworkAssets()
         }
 
         [TestMethod]
-        [DoNotParallelize]
         public void MakeReferencedAssetOriginalItemSpecAbsolute_ResolvesAgainstProjectDirectoryNotProcessCurrentDirectory()
         {
             var testRoot = Path.Combine(AppContext.BaseDirectory, nameof(ComputeReferenceStaticWebAssetItemsTest), Guid.NewGuid().ToString("N"));

@@ -15,7 +15,6 @@
 
 namespace Microsoft.NET.Sdk.StaticWebAssets.Tests;
 
-[DoNotParallelize]
 [TestClass]
 
 public class DiscoverPrecompressedAssetsMultiThreadingTest

@@ -169,7 +169,6 @@ public void Fails_WhenEndpointWithoutAssetExists()
     }
 
     [TestMethod]
-    [DoNotParallelize]
     public void Execute_RelativeTargetPropsFilePath_ResolvesAgainstProjectDirectory_NotProcessCurrentDirectory()
     {
         WithDecoyCwdAndProjectDirectory((projectDir, spawnDir) =>

@@ -9,9 +9,6 @@
 
 namespace Microsoft.NET.Sdk.StaticWebAssets.Tests;
 
-// This test mutates the process-wide current directory, so it must not run
-// concurrently with other tests under MSTest's method-level parallelization.
-[DoNotParallelize]
 [TestClass]
 public class GenerateStaticWebAssetsManifestMultiThreadingTest
 {

@@ -10,9 +10,6 @@
 
 namespace Microsoft.NET.Sdk.StaticWebAssets.Tests;
 
-// This test mutates the process-wide current directory, so it must not run
-// concurrently with other tests under MSTest's method-level parallelization.
-[DoNotParallelize]
 [TestClass]
 public class GenerateStaticWebAssetsPropsFileMultiThreadingTest
 {

@@ -16,11 +16,6 @@
 
 namespace Microsoft.NET.Sdk.StaticWebAssets.Tests;
 
-// Test parallelization is disabled assembly-wide via
-// [assembly:CollectionBehavior(DisableTestParallelization = true)] in
-// LegacyStaticWebAssetsV1IntegrationTest.cs, which already isolates the
-// process-CWD mutation this test performs.
-[DoNotParallelize]
 [TestClass]
 public class MergeConfigurationPropertiesMultiThreadingTest
 {

@@ -9,9 +9,6 @@
 
 namespace Microsoft.AspNetCore.Razor.Tasks;
 
-// This test mutates the process-wide current directory, so it must not run
-// concurrently with other tests under MSTest's method-level parallelization.
-[DoNotParallelize]
 [TestClass]
 public class ReadStaticWebAssetsManifestFileMultiThreadingTest
 {

@@ -15,11 +15,6 @@
 
 namespace Microsoft.NET.Sdk.StaticWebAssets.Tests;
 
-// Test parallelization is disabled assembly-wide via
-// [assembly:CollectionBehavior(DisableTestParallelization = true)] in
-// LegacyStaticWebAssetsV1IntegrationTest.cs, which already isolates the
-// process-CWD mutation these tests perform.
-[DoNotParallelize]
 [TestClass]
 public class StaticWebAssetTaskEnvironmentTests
 {

@@ -10,9 +10,6 @@
 
 namespace Microsoft.AspNetCore.Razor.Tasks;
 
-// This test mutates the process-wide current directory, so it must not run
-// concurrently with other tests under MSTest's method-level parallelization.
-[DoNotParallelize]
 [TestClass]
 public class StaticWebAssetsGeneratePackManifestMultiThreadingTest
 {

@@ -15,11 +15,6 @@
 
 namespace Microsoft.AspNetCore.Razor.Tasks;
 
-// Test parallelization is disabled assembly-wide via
-// [assembly:CollectionBehavior(DisableTestParallelization = true)] in
-// LegacyStaticWebAssetsV1IntegrationTest.cs, which already isolates the
-// process-CWD mutation this test performs.
-[DoNotParallelize]
 [TestClass]
 public class StaticWebAssetsGeneratePackagePropsFileMultiThreadingTest
 {

@@ -10,9 +10,6 @@
 
 namespace Microsoft.NET.Sdk.StaticWebAssets.Tests;
 
-// This test mutates the process-wide current directory, so it must not run
-// concurrently with other tests under MSTest's method-level parallelization.
-[DoNotParallelize]
 [TestClass]
 public class UpdatePackageStaticWebAssetsMultiThreadingTest
 {

diff --git a/test/Microsoft.NET.ToolPack.Tests/GivenThatWeWantToPackAToolProjectWithPackagedShim.cs b/test/Microsoft.NET.ToolPack.Tests/GivenThatWeWantToPackAToolProjectWithPackagedShim.cs
@@ -10,7 +10,6 @@
 namespace Microsoft.NET.ToolPack.Tests
 {
     [TestClass]
-    [DoNotParallelize]
     public class GivenThatWeWantToPackAToolProjectWithPackagedShim : SdkTest
     {
         private string _testRoot;

@@ -14,10 +14,6 @@
 namespace Microsoft.TemplateEngine.Cli.UnitTests.PostActionTests
 {
     [TestClass]
-    // These tests mutate the process-global static Microsoft.DotNet.Cli.Utils.Reporter via
-    // Reporter.SetError, so they cannot run in parallel with each other (MSTest defaults to
-    // method-level parallelism in this repo).
-    [DoNotParallelize]
     public class AddJsonPropertyPostActionTests
     {
         // MSTest has no IClassFixture equivalent; a lazily-initialized static helper

diff --git a/test/dotnet-MsiInstallation.Tests/Framework/VMTestBase.cs b/test/dotnet-MsiInstallation.Tests/Framework/VMTestBase.cs
@@ -9,7 +9,6 @@
 
 namespace Microsoft.DotNet.MsiInstallerTests.Framework
 {
-    [DoNotParallelize]
     public class VMTestBase : SdkTest, IDisposable
     {
         private VirtualMachine _vm;

diff --git a/test/dotnet-aot.Tests/AssemblyInfo.cs b/test/dotnet-aot.Tests/AssemblyInfo.cs