C# Quick Fix / Code Action completely broken in Cursor 3.14+

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

C# Quick Fix / Code Action completely broken in Cursor 3.14+ — MutableDisposable error

Steps to Reproduce

  1. Place the cursor on code that produces a Roslyn Quick Fix.
  2. Press Ctrl + ..
  3. Select any Quick Fix.
  4. Nothing happens.
  5. Check the Developer Tools console.
  6. Observe:
    Trying to set a value on a MutableDisposable that has already been disposed of.

Expected Behavior

Selecting a C# Quick Fix such as:

Add using
Introduce local
Generate members
Other Roslyn Code Actions

should apply the corresponding code change immediately.

Operating System

Windows 10/11

Version Information

Cursor 3.13.25: Works correctly
Cursor 3.14.27: Broken
Cursor 3.15.6: Broken
VS Code with the same project: Works

Does this stop you from using Cursor

No - Cursor works, but with this issue

5

Hey, thanks for the detailed report. The version info, console log, and comparison with VS Code helped a lot.

This is a known issue with code actions Quick Fix and Ctrl+.. It started in 3.14 and affects several language servers, not just C# and Roslyn. We’ve seen the same symptom reported for TypeScript and Dart and Flutter too. We’re tracking it, and a fix is already ready. It’s available in the nightly builds 3.16.0-pre and will ship in one of the next stable releases.

Until the fix lands in stable, you’ve got two options:

  • Stay on 3.13.25, where code actions work correctly.
  • Switch to the nightly channel via Settings → Application → Update, where the issue is already fixed.

I’ll reply here once the fix is in a stable release.