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Migrate from Microsoft VS Code to VSCodium: 6 extension IDs that stop working

6 of the 9 recommended extensions in a sample .vscode/extensions.json stop working when a Python and C++ platform team moves from Microsoft VS Code to VSCodium. It is written in Microsoft's own licence files, checked on 2026-09-29: Pylance and C/C++ may be used "only with Microsoft Visual Studio, Visual Studio for Mac, Visual Studio Code, Azure DevOps, Team Foundation Server, and successor Microsoft products and services", and the Remote Development licence says "You may not use the software if you do not have a license for Microsoft Visual Studio Code."

The second half of the problem is the registry. VSCodium installs extensions from Open VSX, and none of the 15 Microsoft and GitHub extension IDs covered here are on Open VSX. A shared recommendation for one of them simply does nothing in VSCodium. The extension panel does not tell them why, and it does not suggest what to use instead.

The sample

The sample lists: ms-python.python, ms-python.vscode-pylance, ms-toolsai.jupyter, ms-vscode.cpptools, ms-vscode-remote.remote-ssh, ms-vscode-remote.remote-containers, ms-vsliveshare.vsliveshare, ms-dotnettools.csdevkit and ms-vscode.cmake-tools. Three of them are fine: ms-python.python is MIT-licensed and on Open VSX, and so are Jupyter and CMake Tools. The other six are flagged:

• ms-python.vscode-pylance: replace with detachhead.basedpyright
• ms-vscode.cpptools: replace with llvm-vs-code-extensions.vscode-clangd
• ms-vscode-remote.remote-ssh: replace with jeanp413.open-remote-ssh
• ms-vscode-remote.remote-containers: use the MIT devcontainer CLI from a terminal
• ms-vsliveshare.vsliveshare: no Open VSX drop-in; its licence says "solely with Microsoft Visual Studio family of products"
• ms-dotnettools.csdevkit: replace with muhammad-sammy.csharp; its licence says "only with Microsoft Visual Studio Code, vscode.dev, GitHub Codespaces"

Why the MIT Python extension misleads

ms-python.python is MIT, so it is natural to assume the Python stack is open. It is not: the language server most teams rely on, Pylance, is a separate extension with a Microsoft licence. The same split exists for C#: the ms-dotnettools.csharp extension bundles a debugger whose licence says it may be used "only ... with Visual Studio Code, Visual Studio or Xamarin Studio software". A settings.json that pins "python.languageServer": "Pylance" keeps pointing at the restricted server even after the extension list is cleaned, so the lint flags that setting too.

What the lint does

Open an extensions.json, devcontainer.json, settings.json or .gitpod.yml. Each problem line shows up in the Problems panel with the extension ID, the clause quoted from the licence file, and the open replacement ID. Entries under unwantedRecommendations and commented-out lines are ignored, so a cleaned list stays quiet. There are 16 rules: 15 extension IDs and the Pylance setting. Four of them are warnings rather than errors: Remote - Tunnels server, Remote Explorer, GitHub Copilot and GitHub Copilot Chat are not on Open VSX, but the lint does not claim anything about their licences.

The same engine runs on the free web page: paste a list, press Check, read the findings.

It is not legal advice: it reads licence text as published, and it installs nothing. Test basedpyright or clangd on your codebase before the team switches.

Try it

Paste your extensions.json into the free web page, or install the extension and open the file. On the sample, the result is six findings and six swaps.