Hey, thanks for the detailed report. This is a known issue. Plan mode sometimes loses the ability to edit its own .plan.md files and says it can’t modify files.
A few other users are seeing the same thing: Cursor unable to edit a plan.
A couple workarounds that can help:
- Open a new chat
CMD + I, switch back to Plan mode, and try updating the plan again. - Try saying this explicitly in your prompt: “Edit the plan file directly, update the .plan.md” It sometimes helps the model get past the limitation.
- Like you noticed, switching to Agent mode to edit the plan works as a fallback.
For debugging, can you share the Request ID from the chat where Plan mode refused to edit? (three dots in the top right of the chat → Copy Request ID). This will help the team narrow down the issue.
The team is aware of the bug. There’s no timeline yet, but your report helps with prioritization. Let me know if the workarounds help.