Repeated Plan Creation Failures in Composer 1 (“Invalid String to Replace” / Timeout)

Support Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Cursor IDE – Composer 1 (Plan Creation)

When using Composer 1 to generate or update a plan, the tool frequently fails with the errors:

  • “Create plan received invalid string to replace in plan”
  • “Create plan tool call errored or timed out”

This behavior occurs consistently during plan creation or when Cursor attempts to update an existing plan using. The issue started since last week, and happens across all of my cursor accounts I use. Switching to Claude or other models resolve the issue, as the model eliminates the problem entirely, so the issue appears specific to Composer 1’s plan-generation tool integration.

Steps to Reproduce

  1. Open a project in Cursor IDE.
  2. Trigger Composer 1 to create or update a plan.
  3. Wait for the plan tool call to run.
  4. Observe that the plan creation fails with the errors mentioned above.

This reproduces reliably across multiple projects.

Expected Behavior

Composer 1 should successfully generate or update the plan without timing out or emitting invalid-string errors. The plan tool should execute normally.

Screenshots / Screen Recordings

Screenshot 2025-12-01 141206.png
Screenshot 2025-12-01 141206.png335×350 7.26 KB

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.1.42 (user setup)
VSCode Version: 1.105.1
Commit: 2e353c5f5b30150ff7b874dee5a87660693d9de0
Date: 2025-12-01T02:18:26.377Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.26100

For AI issues: which model did you use?

Composer 1

Does this stop you from using Cursor

No - Cursor works, but with this issue

2

Hey, thanks for the report. This is a known issue with the create_plan tool in Composer 1 when creating or editing plans.

Bug: When the tool can’t find valid strings to replace in the plan after several attempts, it times out with the error “Invalid String to Replace”.

Workaround:

  • Copy the markdown content of the plan
  • Open a new agent window
  • Paste the copied plan and continue working there

Similar: Cursor planning mode crash

To pass this to the engineers, please share:

  • Request ID of the stuck request (chat menu top right > Copy Request ID, with Privacy Mode off)
  • Help > Toggle Developer Tools > Console (screenshot of errors at timeout)
  • Reproduction steps: what exactly you asked to do with the plan before the error

I’ll attach your report to the existing issue.

1 Like
3

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