MainThreadCursor disposed error only in specific project

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1

Where does the bug appear (feature/product)?

Somewhere else…

Describe the Bug

Hi,

I’m experiencing an issue where Cursor crashes with “MainThreadCursor disposed” error, but only in one specific project.

Environment:

  • Windows 11 Home 64-bit
  • Cursor (latest version, fresh install)
  • Next.js + Supabase project

What I’ve tried:

  • Reinstalled Cursor completely
  • Deleted workspaceStorage cache
  • Removed node_modules folder
  • Added .cursorignore
  • Disabled all extensions
  • Moved project to C:\ root
  • Removed read-only attribute

The same setup works fine in other projects.

Error message:
MainThreadCursor disposed while stream was active
ControlledExecDisposedError: MainThreadCursor disposed

Request ID: 76f21907-5caf-4e76-883d-6b1b104070aa

Any help would be appreciated!

Steps to Reproduce

  1. Open a specific Next.js + Supabase project
  2. Open a new chat window
  3. Type any message (e.g. “Hi”)
  4. Error appears immediately: “MainThreadCursor disposed”

Expected Behavior

AI should respond normally to messages

Screenshots / Screen Recordings

bug.jpg
bug.jpg1272×797 66.4 KB

Operating System

Windows 10/11

Version Information

Version: 2.6.11 (user setup)
VSCode Version: 1.105.1
Commit: 8c95649f251a168cc4bb34c89531fae7db4bd990
Date: 2026-03-03T18:57:48.001Z
Build Type: Stable
Release Track: Default
Electron: 39.6.0
Chromium: 142.0.7444.265
Node.js: 22.22.0
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.26100

For AI issues: which model did you use?

claude-sonnet-4.6 (Auto mode)

For AI issues: add Request ID with privacy disabled

76f21907-5caf-4e76-883d-6b1b104070aa

Additional Information

This error only occurs in one specific project (Next.js + Supabase). Other projects work fine. Tried reinstalling Cursor, clearing cache, removing node_modules, disabling all extensions - none worked.

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

3

Hey, I see a screenshot showing a Connection Error and the extension host crashing. Since you’ve already tried the usual steps (reinstalling, clearing cache, disabling extensions, etc.), let’s dig deeper.

A few things to try:

  • Delete the workspace state for this project: Close Cursor, then go to %APPDATA%\Cursor\User\workspaceStorage\, find and delete the folder for this project (sort by date modified, the most recent one is probably it). Then open the project again.
  • Check the DevTools logs: Open the problem project, then go to Help > Toggle Developer Tools > Console. Try sending a chat message and see what errors show up right before the crash. Copy those logs here, they’ll help identify the real cause.
  • Try creating a completely new project with the same stack (Next.js + Supabase) and move your files over one by one. This can help figure out if a specific file or config is triggering the issue.

Also, is there anything unusual in this project’s .cursorrules file or in the MCP server configs? And roughly how many files and folders are in the project?

Let me know what you find in the DevTools console.