The IDE fully hangs when outputting a Plan

[tk01]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Every time I ask something in Plan mode, when it starts generating the plan document it will stop a few lines in, and the entire Cursor application freezes until the OS’s “The window is not responding” message appears. Cursor never responds again until forcibly closed.

Steps to Reproduce

Make a query in Plan mode

Expected Behavior

Cursor outputs the Plan and keeps functioning

Operating System

MacOS

Version Information

Version: 2.4.21
VSCode Version: 1.105.1
Commit: dc8361355d709f306d5159635a677a571b277bc0
Date: 2026-01-22T16:57:59.675Z (4 days ago)
Build Type: Stable
Release Track: Default
Electron: 39.2.7
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Darwin arm64 24.3.0

For AI issues: which model did you use?

Claude Opus

Does this stop you from using Cursor

Yes - Cursor is unusable

[deanrie]

Hey, this is a known issue. There are other reports with the same symptoms on 2.4.21 with Plan mode and Opus: Cursor froze & leaked memory during plan mode with Opus 4.5

The bug is logged. To help us prioritize your report, can you share the Request ID from the affected chat? (Chat context menu > Copy Request ID)

[Bovej (Bove)]

Same problem - it even crashes when Cursor tries to open a “plan” from the .cursor/plans folder. On Mac:

The window terminated unexpectedly (reason: ‘crashed’, code: ‘11’)

Update: could have something to do with the Markdown Formatter in combination with very long plans.

[tk01]

Request ID: 2dc6fd1a-f79c-4480-9d89-76386368ea05

[Pawel_Kotowski (Paweł Kotowski)]

same

[tk01]

It looks like this has been fixed, at least for me