MCP servers disconnect repeatedly - "Not connected" error

[R.hoejland]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I’m experiencing repeated MCP disconnections during normal use.

Setup:

• Cursor 2.3.26 (latest)
• Windows 10
• Multiple MCP servers: cursor-browser-extension (Playwright) + Supabase

What happens:
Both MCP servers show {"error":"Not connected"} at the same time. They work fine initially, then after some time (variable), they both fail together.

Observations:

• It’s not one specific MCP - both fail simultaneously
• This suggests the issue is in Cursor’s MCP connection layer
• Only a full restart (File > Exit) fixes it temporarily
• Window reload doesn’t help

My workspace:
OneDrive-synced folder (could be related?)

Reproduction:

1. Use MCP tools normally
2. After a while, both MCPs return “Not connected”
3. Restart Cursor to temporarily fix

Has anyone else seen this? Any known workarounds beyond restarting?

Thanks!

Steps to Reproduce

1. Configure multiple MCP servers (e.g., cursor-browser-extension + Supabase)
2. Verify both show green/connected status
3. Use MCP tools normally for 10-30 minutes
4. Trigger a browser navigation or complex operation
5. Both MCPs return {“error”:“Not connected”} simultaneously
6. Only full restart (File > Exit) restores connection

Expected Behavior

MCP connections should remain stable throughout the session without requiring restarts.

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.3.26
VSCode Version: 1.105.1
Commit: bdbdd3f2cf698f583c5cdd2a6dc0f5aec4ed5f90

For AI issues: which model did you use?

Claude Opus 4 (Agent mode)

Additional Information

Using MCP servers configured in .cursor/mcp.json
Both Supabase MCP and cursor-browser-extension fail at the exact same moment.
Workspace is on OneDrive-synced folder.

Does this stop you from using Cursor

No - Cursor works, but with this issue

[deanrie]

Hey, thanks for the report. This is a known issue with SSE connections for MCP servers. Similar reports were posted here: Linear MCP commonly errors out.

Some related issues were fixed recently. Can you try:

• Update to the latest version (Help > Check for Updates)
• If it still happens, try toggling the MCP servers in Settings instead of doing a full restart. It’s faster.

It’d also help to check the logs:

• Output panel (View > Output) > select “MCP” or the specific server name
• You should see the exact error there, like SSE error: ...

About OneDrive, it’s unlikely to be the cause, but you can try moving the project to a normal folder just to test.

If it happens again on the latest version, send the logs and we’ll take a closer look.