This is a known bug. After certain updates, the Extension Host can fail to initialize due to leftover extension state from the previous version, which causes exactly the symptoms you’re seeing (Authentication UI, Cursor Tab, Agent Endpoint, and Codebase Indexing all timing out).
A fix for the underlying race condition shipped in your version (3.6.21), but it doesn’t automatically clean up pre-existing state from the update. A standard reinstall also won’t clear it since the extension data lives in a separate folder. Here’s what should fix it:
-
Fully quit Cursor – open Activity Monitor, search for “Cursor,” and force-quit all Cursor processes
-
Delete the extension cache:
rm -rf ~/Library/Application\ Support/Cursor/Cache
- Remove the obsolete extension marker (if it exists):
rm ~/Library/Application\ Support/Cursor/User/extensions/.obsolete
- Relaunch Cursor
If that doesn’t resolve it, try launching with extensions disabled to rule out a corrupted extension:
/Applications/Cursor.app/Contents/MacOS/Cursor --disable-extensions
If that works, you can re-enable extensions normally on the next launch.
You may also find this related thread helpful, where our engineering team confirmed the root cause and fix.
Let me know if that gets you back up and running!