Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
Chat session becomes seemingly corrupted and unable to enter new messages. Upon attempt of message input, the input is reverted and remains in the text input without submission.
Steps to Reproduce
I’m not sure how to consistently reproduce, however, it has happened several times especially when I ask Cursor to edit the mcp json config that I have had opened after navigating to settings > tools > edit pencil/mcp
In some cases I have attached the mcp.json file as context to the chat header, or inline in message.
This seems to trigger the condition most times.
From here, Cursor becomes unusable; even starting new chats will usually not work and accept input.
Shutting down Cursor (all Cursor windows) and restarting, sometimes needing to do multiple, eventually succeeds.
I’m unsure if Cursor is allowed to edit this file; it has successfully in the past, some versions ago.
This has happened before from time to time, but I can’t recall the exact circumstances back then.
Expected Behavior
Ideally, edit the mcp.json config as instructed.
Operating System
Windows 10/11
Current Cursor Version (Menu → About Cursor → Copy)
Version: 1.4.6 (user setup)
VSCode Version: 1.99.3
Commit: 8bdbd55db6885f3d79f73cdacca5fcedef93d360
Date: 2025-08-15T02:08:45.149Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.26100
Additional Information
WSL
Does this stop you from using Cursor
Yes - Cursor is unusable