Hey, thanks for the report. This is a known issue in Planning Mode that appeared in version 2.1.0 and is currently being investigated by the team.
The team is tracking it here: Planner broken in 2.1.0
Could you share a Request ID from a failed planning attempt so we can link your case?
Chat menu (top right) → Copy Request ID
Temporary workarounds:
- Try starting a new plan instead of editing existing ones
- If you’ve saved plans to .cursor/plans/, you can edit the markdown there directly
The team is actively working on a fix.