All MCP servers fail to start, error Failed to acquire MessagePort

Support Bug Reports
1

All of my MCP servers (Maven, file, database, git etc.) cannot connect in Cursor, they throw the identical error repeatedly: Failed to acquire MessagePort for response channel 'vscode:createMcpProcessChannelConnectionResult'

What I tested:

  1. Only keep one single MCP server in mcp.json, remove all others, error still exists.
  2. Run MCP startup command manually in terminal, every server runs stable without crash.
  3. Killed all cursor, node, java background processes, cleared Cursor global storage cache.
  4. Created empty workspace with minimal MCP config, no extra extensions.
  5. Windows 11, Cursor latest version.

My question:

Since every MCP hits the same MessagePort error, this should be an internal Cursor Electron communication bug instead of wrong MCP config. Is there any known fix or compatible version for this issue?

4

hey @ruochan, thanks for your message, this is a known issue, a thread was already opened there : MCP fails to start — utility process never reaches `ipcReady` (Windows)

for now, there is no ETA for when the fix will land, but the team is aware and working on a fix!

7

Hey, quick add-on to my answer above. This is a known bug with the MCP utility process cold start. The handshake between the renderer and Cursor.exe --type=utility doesn’t finish, so the MessagePort never gets created and all servers crash right away, not just one config. The fact that servers start reliably when you run them manually in a terminal matches this.

On Windows this is often environment-related. Here’s what to check and try:

  1. Reload Window: Cmd+Shift+P or Ctrl+Shift+P then Developer: Reload Window. This can sometimes unstick a stuck state.
  2. Temporarily keep the number of enabled MCP servers to a minimum. Fewer parallel cold starts means a better chance to complete before the timeout.
  3. Use per-server Reconnect in the MCP settings instead of doing a full restart.
  4. Check whether antivirus, EDR, or Core Isolation HVCI is blocking Cursor.exe --type=utility, especially on corporate-managed devices. This is the most common cause on Windows.

I can’t share an ETA for a fix. Tracking is mostly happening in the main thread: MCP fails to start — utility process never reaches `ipcReady` (Windows). Subscribe there so you don’t miss updates. Let me know if any of the steps helped.