Agent stops working - Extension Error

[Gh05stt]

Describe the Bug

When using plan, I get an error saying
“Extension host terminated unexpectedly 3 times within the last 5 minutes”
and the agent stops responding, if I try to send a message, it doesn’t send unless i restart the extensions. Restarting works temporarily (for about 30 seconds) and then it fails again

Steps to Reproduce

1. Use plan mode
2. Send prompt
3. Wait for extensions to crash

Expected Behavior

Agent/Plan mode should complete tasks properly before stopping

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.2.20 (Universal)
VSCode Version: 1.105.1
Commit: b3573281c4775bfc6bba466bf6563d3d498d1070
Date: 2025-12-12T06:29:26.017Z (1 day ago)
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Darwin arm64 25.1.0

For AI issues: which model did you use?

Sonnet 4.5,
Opus 4.5 high thinking

For AI issues: add Request ID with privacy disabled

Request ID: f50ca796-0e4c-45ea-953f-807db47b4a35

Additional Information

Using an M-series MacOS device

Does this stop you from using Cursor

Yes - Cursor is unusable

[deanrie]

Hey, thanks for the report. This is a known issue with the extension host, and the team is working on a fix.

For diagnostics, please try:

1. Check MCP servers: Settings > MCP - disable all servers (especially GitHub, Atlassian), then restart Cursor
2. Test without extensions: run cursor --disable-extensions from the terminal and try Plan mode
3. Check processes: CMD+Shift+P > Developer: Open Process Explorer - review extensionHost resource usage
4. Console errors: Help > Toggle Developer Tools > Console tab - take a screenshot of errors when the crash occurs

Try these and let me know the results.