Question: I would like to install previous version of Python extension for VSCode (ms-python.python) to troubleshoot something, but when I am trying to use context menu with "Install another version..." I just have an error "server returned 404"

Answer: 
This can be done using "Install Another Version" option available with VS Code extension store.

1. Go to extensions.
2. Click on Gear Icon for the installed extension
3. Click on Install Another Version
4. And select the version you wish to install
[![Select Version Option](https://i.stack.imgur.com/GTSvu.png)](https://i.stack.imgur.com/GTSvu.png)
The 404 issue is a [bug in the VS Code marketplace](https://github.com/microsoft/vscode/issues/99699). They are actively working to fix the problem.