Issues with C# extension with VS-Code on Arch Linux

Question

My suggestions stuff on vscode for C# suddenly stopped (not completely) but not the way it was before (not actual inline suggestions like before, now I only see snippets etc), and I'm seeing error logs on output window in VSCode regarding the C# extension. I have installed C# Dev, C#, .NET install tool, Intellisense for C# official microsoft extensions. I've already installed .NET 9.0.9.sdk110-1 properly on this system through the package manager (pacman) and my system is uptodate too.

Here is the error log,

2025-10-09 13:59:03.083 [info] Locating .NET runtime version 9.0.1
2025-10-09 13:59:03.262 [info] Dotnet path: /usr/share/dotnet/dotnet
2025-10-09 13:59:03.262 [info] Activating C# + C# Dev Kit + C# IntelliCode...
2025-10-09 13:59:03.404 [info] [stdout] info: Program[0]
      Server started with process ID 27285

2025-10-09 13:59:04.073 [info] [stdout] fail: Microsoft.CodeAnalysis.Remote.ExportProviderBuilder[0]
      Encountered errors in the MEF composition:
      ----- CompositionError level 1 ------
      Microsoft.VisualStudio.Copilot.Roslyn.Completion.CSharpMethodCallerBlueprintProvider.ctor(joinableTaskContext): expected exactly 1 export matching constraints:
          Contract name: Microsoft.VisualStudio.Threading.JoinableTaskContext
          TypeIdentityName: Microsoft.VisualStudio.Threading.JoinableTaskContext
      but found 0.
         part definition Microsoft.VisualStudio.Copilot.Roslyn.Completion.CSharpMethodCallerBlueprintProvider
      
      Microsoft.CodeAnalysis.ExternalAccess.Copilot.Internal.SemanticSearch.CopilotSemanticSearchQueryExecutor.ctor(workspaceProvider): expected exactly 1 export matching constraints:
          Contract name: Microsoft.CodeAnalysis.Host.IHostWorkspaceProvider
          TypeIdentityName: Microsoft.CodeAnalysis.Host.IHostWorkspaceProvider
      but found 0.
         part definition Microsoft.CodeAnalysis.ExternalAccess.Copilot.Internal.SemanticSearch.CopilotSemanticSearchQueryExecutor
      
      Microsoft.VisualStudio.Copilot.Roslyn.Completion.CSharpReferencedSymbolDefinitionSnippetProvider.ctor(joinableTaskContext): expected exactly 1 export matching constraints:
          Contract name: Microsoft.VisualStudio.Threading.JoinableTaskContext
          TypeIdentityName: Microsoft.VisualStudio.Threading.JoinableTaskContext
      but found 0.
         part definition Microsoft.VisualStudio.Copilot.Roslyn.Completion.CSharpReferencedSymbolDefinitionSnippetProvider
      
      Microsoft.VisualStudio.Copilot.Roslyn.Completion.CSharpMemberAccessSymbolBlueprintProvider.ctor(joinableTaskContext): expected exactly 1 export matching constraints:
          Contract name: Microsoft.VisualStudio.Threading.JoinableTaskContext
          TypeIdentityName: Microsoft.VisualStudio.Threading.JoinableTaskContext
      but found 0.
         part definition Microsoft.VisualStudio.Copilot.Roslyn.Completion.CSharpMemberAccessSymbolBlueprintProvider
      
      Microsoft.CodeAnalysis.ExternalAccess.Pythia.PythiaSignatureHelpProvider.ctor(implementation): expected exactly 1 export matching constraints:
          Contract name: Microsoft.CodeAnalysis.ExternalAccess.Pythia.Api.IPythiaSignatureHelpProviderImplementation
          TypeIdentityName: Microsoft.CodeAnalysis.ExternalAccess.Pythia.Api.IPythiaSignatureHelpProviderImplementation
      but found 0.
         part definition Microsoft.CodeAnalysis.ExternalAccess.Pythia.PythiaSignatureHelpProvider
      
      Microsoft.CodeAnalysis.ExternalAccess.Copilot.Internal.CodeMapper.CSharpMapCodeService.ctor(service): expected exactly 1 export matching constraints:
          Contract name: Microsoft.CodeAnalysis.ExternalAccess.Copilot.CodeMapper.ICSharpCopilotMapCodeService
          TypeIdentityName: Microsoft.CodeAnalysis.ExternalAccess.Copilot.CodeMapper.ICSharpCopilotMapCodeService
      but found 0.
         part definition Microsoft.CodeAnalysis.ExternalAccess.Copilot.Internal.CodeMapper.CSharpMapCodeService
      
      
      Microsoft.VisualStudio.Composition.CompositionFailedException: Errors exist in the composition.
         at Microsoft.VisualStudio.Composition.CompositionConfiguration.ThrowOnErrors()
         at Microsoft.CodeAnalysis.Remote.ExportProviderBuilder.CheckForAndReportCompositionErrors(CompositionConfiguration configuration, ComposableCatalog catalog) in /_/src/Workspaces/Remote/Core/ExportProviderBuilder.cs:line 208

2025-10-09 13:59:04.346 [info] [stdout] {"pipeName":"/tmp/ce1f17e8.sock"}

2025-10-09 13:59:04.347 [info] received named pipe information from server
2025-10-09 13:59:04.347 [info] client has connected to server
2025-10-09 13:59:04.441 [info] [Program] Language server initialized
2025-10-09 13:59:05.575 [info] [textDocument/_vs_getProjectContexts] [Microsoft.CodeAnalysis.LanguageServer.DotnetCliHelper] Using dotnet executable configured on the PATH
2025-10-09 13:59:05.723 [info] [textDocument/_vs_getProjectContexts] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsProjectSystem] Failed to obtain virtual project for '/home/shinzo/Code/CS/GameStore/src/GameStore.API/Repositories/UnitOfWork.cs' using dotnet run-api. Falling back to directly creating the virtual project.
2025-10-09 13:59:06.049 [info] [textDocument/_vs_getProjectContexts] [Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager] .NET BuildHost started from /home/shinzo/.vscode/extensions/ms-dotnettools.csharp-2.93.22-linux-x64/.roslyn/Microsoft.CodeAnalysis.LanguageServer reloading to start from /usr/share/dotnet/dotnet to match necessary SDK location.
2025-10-09 13:59:07.095 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project /home/shinzo/Code/CS/GameStore/src/GameStore.API/GameStore.API.csproj loaded by C# Dev Kit
2025-10-09 13:59:07.198 [warning] [textDocument/_vs_getProjectContexts] [LanguageServerProjectLoader] Project /home/shinzo/Code/CS/GameStore/src/GameStore.API/Repositories/UnitOfWork.csproj has unresolved dependencies
2025-10-09 13:59:07.236 [info] [textDocument/_vs_getProjectContexts] [LanguageServerProjectLoader] Successfully completed load of /home/shinzo/Code/CS/GameStore/src/GameStore.API/Repositories/UnitOfWork.cs
2025-10-09 13:59:07.461 [error] [workspace/_roslyn_restore] [Microsoft.CodeAnalysis.LanguageServer.Handler.RestoreHandler] Restore completed with errors.
2025-10-09 13:59:07.464 [info] [textDocument/_vs_getProjectContexts] [LanguageServerProjectLoader] Completed (re)load of all projects in 00:00:01.921643

dotnet command is working correctly and, /usr/share/dotnet/dotnet is working correctly too. So far, I've tried reinstalling extensions, removing extension cache(.vscode/extensions/*) and installing again, but nothing worked. But did not tried completely removing vscode or anything yet.

Answer 1

After Aparslan's comment about version mismatch, I tried to rollback my C# and C# dev extensions from current versions to previous versions (C# Dev - v1.50.51 & C# 2.90.60) and the issue got fixed. IDK, but according to dotnet.microsoft.com, I'm using the latest version. And 9.0.9.sdk110-1 is the latest version on arch repositories.