Describe the bug
MCP initialization stucked at "Set up MCP Proxy" with node_modules/@modelcontextprotocol/sdk/dist/esm/server/sse.js:103
throw new Error("Not connected") on Windows 11 24H2. I doubt that this shouldn't be a bug but could be misconfiguration.
To Reproduce
Steps to reproduce the behavior:
- Minimal walkthrough of installation.
- npm cache clean --force
- Copy&Paste simple MCP server.py at QuickStart. (https://github.com/modelcontextprotocol/python-sdk?tab=readme-ov-file#quickstart)
- mcp dev server.py
- Error with SSE. Logs below:
Starting MCP inspector...
⚙️ Proxy server listening on port 6277
🔍 MCP Inspector is up and running at http://127.0.0.1:6274 🚀
Stdio transport: command=C:\Program Files\Python311\Scripts\uv.exe, args=run,--with,mcp,mcp,run,test_server.py
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
file:///C:/.../node_modules/@modelcontextprotocol/sdk/dist/esm/server/sse.js:103
throw new Error("Not connected");
^
Error: Not connected
at SSEServerTransport.send (file:///C:/.../node_modules/@modelcontextprotocol/sdk/dist/esm/server/sse.js:103:19)
at Socket.<anonymous> (file:///C:/.../node_modules/@modelcontextprotocol/inspector/server/build/index.js:101:33)
at Socket.emit (node:events:507:28)
at addChunk (node:internal/streams/readable:559:12)
at readableAddChunkPushByteMode (node:internal/streams/readable:510:3)
at Readable.push (node:internal/streams/readable:390:5)
at Pipe.onStreamRead (node:internal/stream_base_commons:189:23)
Node.js v23.11.0
Expected behavior
Connection through SSE should be established.
Screenshots
I shall provide detailed log output and actively participating discussion. I'd be glad to hear if there's anything I could provide.
Desktop (please complete the following information):
- OS: Windows 11 24H2
- Browser Thorium / Edge / Chromium
- Version 26100.3624
Additional context
Gratitude on active development. Shame on me triggering low-level weird bugs.
Describe the bug
MCP initialization stucked at "Set up MCP Proxy" with node_modules/@modelcontextprotocol/sdk/dist/esm/server/sse.js:103
throw new Error("Not connected") on Windows 11 24H2. I doubt that this shouldn't be a bug but could be misconfiguration.
To Reproduce
Steps to reproduce the behavior:
Expected behavior
Connection through SSE should be established.
Screenshots
I shall provide detailed log output and actively participating discussion. I'd be glad to hear if there's anything I could provide.
Desktop (please complete the following information):
Additional context
Gratitude on active development. Shame on me triggering low-level weird bugs.