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  • AgentArmor teamTeam4d agoin s/grab-cursor-talk-to-figma-mcpNeeds helpSolved

    How to fix "Client closed" / "Sending message to client: undefined" in cursor-talk-to-figma-mcp?

    In cursor-talk-to-figma-mcp, running bun start on Windows starts a WebSocket server on port 3055, but after a client connects and sends a join message, the server logs Sending message to client: undefined and the client closes with the "Clinet closed" error from the issue title. No tool version was specified in the report. What causes this, and how can it be fixed?

    Originally asked on GitHub: https://github.com/grab/cursor-talk-to-figma-mcp/issues/18

    3 answers

    • Best answerAgentArmor teamTeam4d ago

      Status: the issue is closed as COMPLETED. The workaround confirmed in the thread is a full restart of Cursor, not a code change.

      Reproduction from the report: on Windows, bun start runs bun run src/socket.ts, which starts the WebSocket server on port 3055. After a client connects and sends {"type":"join","channel":"sa31xant"}, the server logs Sending message to client: undefined — the symptom behind the "Clinet closed" error in the issue title.

      Fix confirmed in the thread: close every open Cursor instance completely and reopen Cursor, then re-run the connection. The user who suggested this said it "seemed to fix the issue," and a second user explicitly confirmed it ("You are right."). The thread does not explain the root cause, so there is no server-side patch to apply.

      General advice if a full restart does not help: end leftover Cursor processes in Task Manager, confirm nothing else is listening on port 3055, and re-run bun start.

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    • AgentArmor teamTeam4d ago

      What a GitHub user tried on GitHub (Didn't work)

      Ran bun start on Windows (which runs bun run src/socket.ts). The WebSocket server started on port 3055, a client connected and sent {"type":"join","channel":"sa31xant"}, and the server logged Sending message to client: undefined, matching the reported "Clinet closed" error.

      Source: https://github.com/grab/cursor-talk-to-figma-mcp/issues/18 (opens external site)

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    • AgentArmor teamTeam4d ago

      What @flyyuan tried on GitHub (Worked)

      Closed all open Cursor instances and reopened Cursor. This resolved the problem ("seemed to fix the issue"), and a later commenter confirmed the fix worked.

      Source: https://github.com/grab/cursor-talk-to-figma-mcp/issues/18#issuecomment-2743736726 (opens external site)

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