There was an error activating the remote language server, c#/Visual Basic Language Server client

Question

When I open any project in Microsoft Visual Studio Community 2019 Version 16.8.4, even a simple newly created .net core console project. I get the error message:

There was an error activating the remote language server, c#/Visual Basic Language Server client.

Afterwards there is no IntelliSense and even though I am able to run a build of the project no errors or warnings appear in visual studio.

The activity monitor log shows the following errors:

• Still unable to load MEF component DLL: Could not load file or assembly 'Microsoft.VisualStudio.CppSvc.Internal, Version=16.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft\CodeAnalysis\Microsoft.VisualStudio.CodeAnalysis.VCPlugin.dll

• Still unable to load MEF component DLL: Could not load file or assembly 'Microsoft.Windows.Simulator.Client, Version=16.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. c:\program files (x86)\microsoft visual studio\2019\community\common7\ide\commonextensions\platform\diagnosticshub\Microsoft.DiagnosticsHub.VisualStudio.Package.dll

• Still unable to load MEF component DLL: Could not load file or assembly 'Microsoft.VisualStudio.VC.RecommendationProvider, Version=16.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO\2019\COMMUNITY\COMMON7\IDE\EXTENSIONS\MICROSOFT\INTELLICODE\IntelliCodeCpp.dll

I have tried to restart visual studio, restart windows, repair visual studio, uninstall visual studio and install it again. I have run the netFxRepairTool. Still running into the issue.

The files, that are mentioned in the log are all present at the expected location.

Answer 1

A fix was provided by Microsoft for this issue. See https://developercommunity2.visualstudio.com/t/There-was-an-error-activating-the-remote/1313889?entry=problem for details. You can download the fix at https://visualstudio.microsoft.com/downloads/

Answer 2

I was able to get rid of the errors that are shown in the activity log by doing the following:

1. I have deinstalled .NET Core SDK 1.0.0 (x64) Installer (x64)
2. Repaired Visual Studio
3. Restarted Windows
4. Installed .NET desktop environment (via visual studio installer)

Now all errors in the activity log are gone, but Visual studio is still not working. It is still showing the same error as before:

There was an error activating the remote language server, c#/Visual Basic Language Server client.

Now I have the following warnings in my activity log (these havn't been there before):

• Request for "Microsoft.VisualStudio.Shell.Internal.SettingsManager (1.0)" from Process denied because the service is only exposed RemoteExclusiveClient, LiveShareGuest.

• Request for proxy to "Microsoft.VisualStudio.Shell.Internal.SettingsManager (1.0)" is declined: ServiceAudienceMismatch.

Then I removed Visual Studio 2019 and installed Microsoft Visual Studio Community 2019 Preview 3.0. Now everything is up and running again. Please be aware that it wasn't enough to install the preview in parallel to the old version. The old version had to be removed first, before the error disappeared.