Command 'Python: Restart Language Server' resulted in an error (command 'python.analysis.restartLanguageServer' not found)

[ewerybody]

Hello, there!
I just saw the news in the release notes of 2020.8.101144: 'Add "Restart Language Server" command.' and was excited!
This way I just got the notion about a completely new background Language Server, as a dedicated replacement for Jedi? 👍

I see that note about the new language server and the possible relation but this seems like a feature above the language server itself! So yes: If I set python.languageServer to Pylance there are other issues but I can restart with this command 👍

Now if it's vscode-python that starts Jedi as a language server. That command should be able to restart it?

Environment data

• VS Code version: 1.48.0
• Extension version: 2020.8.101144
• OS and version: Windows 10 Pro 2004
• Python version: 2.7.18 / 3.8.4
• Value of the python.languageServer setting: Jedi

[NOTE: If you suspect that your issue is related to the Microsoft Python Language Server (python.languageServer: 'Microsoft'), please download our new language server Pylance from the VS Code marketplace to see if that fixes your issue]

Expected behaviour

Language Server restarts

Actual behaviour

Error message:

Command 'Python: Restart Language Server' resulted in an error (command 'python.analysis.restartLanguageServer' not found)

Steps to reproduce:

1. Set language server to Jedi
2. in command palette call Python: Restart Language Server

[karthiknadig]

Looks like we have some issue with command registration. See related (but reverse issue) #13441

[JP01]

I'm getting this even with language server = pylance
It won't run for anything! :(
For some reason no autocomplete/gotos work anymore :(

[karthiknadig]

@JP01 Try this and see if it helps. Some times it is just a bad install.
Looks like you might have a bad update. Do the following to remove stale versions of the extension:

1. Uninstall Python extension (if you have pylance uninstall it first).
2. Close all instances of VS Code.
3. Go to, %USERPROFILE%/.vscode/extensions (on windows) or ~/.vscode/extensions on Linux/Mac.
4. Delete any folder with the name starting with ms-python.python*
5. Start VS Code, and install Python extension (also pylance if you uninstalled it in step 1).

[alanwilter]

Thanks @karthiknadig, that seemed to work but, honestly, I tried VS a couple of years ago and because of issues like that I gave up and went back to Eclipse, yep.

Now I'm trying again, I was quite happy until now... Is there any method to keep the latest working launch.json and settings.json (both User and Workspace) saved for prompt recover?

[alanwilter]

This issue seems to happen to me every time I try to use JediLSP. BTW, what's difference from the usual Jedi?

[karthiknadig]

@alanwilter There is a option to sync your settings. This is a good question to ask on the VS Code repository.

JediLSP is an experimental version of Language Server implemented based on the Jedi library. When you set Language Server as Jedi, we import jedi library and manually query it for the completion details, hover, etc. With JediLSP, it uses Jedi library over the Language Server Protocol, this allows us to extend jedi's capabilities easily. Right now, you get few additional things when using JediLSP, rename, refactoring, and code outline. But this is still experimental, and we are still working out the issues with it, so we have both jedi and jediLSP available to slelect.

[alanwilter]

Thanks @karthiknadig, not my intention to hijack this issue. Stackoverflow, e.g., does not know yet about JediLSP and I do believe it is the one causing the issue reported here, though I also noticed that Visual Studio IntelliCode Insiders is not playing well with Pylance.

[sloria]

I am also seeing that the Python language server is failing to start (even with Pylance installed and enabled). I've tried the following:

• Verified that I'm using the latest versions of all extensions
• Verified that I'm on the lastest version of VS Code (1.55.0)
• Followed the steps suggested above for re-installing the Python and Pylance extensions
• Uninstalling VS Code, removing ~/.vscode, re-installing VS Code, then syncing settings using the Settings Sync extension.

If I try to run Python: Restart Language Server I get Command 'Python: Restart Language Server' resulted in an error (command 'python.analysis.restartLanguageServer' not found).

Please let me know if I can provide any more useful information for diagnosing this.

[sloria]

Ah, after I re-created my virtualenv (I'm using pyenv+pyenv-virtualenv), restarted VS Code, then re-selected the interpreter using Python: Select Interpreter, the issue is resolved for me.

[fharper]

@JP01 Try this and see if it helps. Some times it is just a bad install. Looks like you might have a bad update. Do the following to remove stale versions of the extension:

1. Uninstall Python extension (if you have pylance uninstall it first).
2. Close all instances of VS Code.
3. Go to, %USERPROFILE%/.vscode/extensions (on windows) or ~/.vscode/extensions on Linux/Mac.
4. Delete any folder with the name starting with ms-python.python*
5. Start VS Code, and install Python extension (also pylance if you uninstalled it in step 1).

Solved my problem.