ERROR_EXTENSION_HOST_TIMEOUT on two Windows PCs — reboot often required

[Nilton_RodriguesN (Nilton)]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

The Agent chat fails with ERROR_EXTENSION_HOST_TIMEOUT on two different Windows machines (desktop and notebook). After the error, every new chat fails. Reload Window and killing Cursor.exe in Task Manager often do not recover the app; a full computer reboot is sometimes the only fix.

This is not a single-machine hardware issue. The request appears to fail locally (extension host unresponsive) before reaching the backend.

Steps to Reproduce

Intermittent; cannot force it every time. Typical sequence:

1. Use Cursor IDE Agent chat normally on Windows (sometimes for hours).
2. Submit a new Agent prompt.
3. UI stays on “taking longer than expected”, then shows Agent Execution Timed Out.
4. New chats keep failing with the same error.
5. Reload Window / Task Manager kill of Cursor.exe often does not recover.
6. Full Windows reboot restores Agent until it happens again.

Reproduced on two PCs: Windows 11 desktop and a Windows notebook.

Expected Behavior

The Agent should start. If the extension host stalls, Reload Window or fully quitting Cursor.exe should recover without a full OS reboot.

Screenshots / Screen Recordings

Operating System

Windows 10/11

Version Information

Cursor IDE 3.17.19 (Help > About Cursor)

For AI issues: which model did you use?

Happens with Agent in Cursor IDE regardless of model (client-side extension host timeout; request often never reaches the backend). Last session used Auto / Grok.

For AI issues: add Request ID with privacy disabled

07a47943-854f-4ba7-9bc0-64fb9c013c77 (2026-08-26)

Note: this ID was captured when the error appeared. I did not reproduce again with Privacy Mode off. Happy to capture a fresh Request ID with Share Data enabled if needed.

Additional Information

Workarounds tried:

• Reload Window
• Kill all Cursor.exe in Task Manager
• Full computer restart (sometimes the only thing that works)

Screenshot of the error dialog is attached.

Also happens on a second Windows machine (notebook), same symptom.

Does this stop you from using Cursor

Yes - Cursor is unusable

[deanrie]

Hey, thanks for the detailed report. I checked the Request ID you shared and it never reached our servers, which matches your guess: the component that runs Agent commands is hanging on your machine before the request ever goes out. If the request never leaves your machine, a new Request ID won’t add much, what’s much more useful is the Extension Host logs at the time of the hang.

How to get them: View > Output, then in the dropdown on the right pick Extension Host and copy paste what you see there, especially any lines that mention cursor-agent-exec or PowerShell.

For now, here are two things to try, both helped other Windows users with the same symptom:

• If PowerShell is restricted or blocked on those machines, sometimes due to corporate software or policies, set Git Bash as the default terminal. Install Git for Windows, then Ctrl+Shift+P > Preferences: Open User Settings (JSON) and add:

  "terminal.integrated.profiles.windows": {
    "Git Bash": { "path": "C:\\Program Files\\Git\\bin\\bash.exe" }
  },
  "terminal.integrated.defaultProfile.windows": "Git Bash"
  

  If Git is installed somewhere else, update the path. After that, fully close and reopen Cursor, not Reload Window, do a real restart.

• Add these folders to your antivirus or security tool exclusions, scanning on launch can hang the process that handles Agent commands:

  • %LOCALAPPDATA%\Programs\cursor\
  • %APPDATA%\Cursor\

One more thing about only a reboot helping: after you kill Cursor in Task Manager, check the Details tab. If some Cursor.exe is still running there, that would explain why reboot fixes it but killing the app doesn’t.

Let me know what the Extension Host logs show and whether the workarounds helped. With the logs we can narrow down the exact cause.