L4 - Unable to spin up a MCP Inspector

[Balaji.Illur]

Hi Team,
I am getting below error in the terminal once I try to connect to MCP server via Model inspector. Please need guidance on the same. @TMosh , request you look at this issue.

Looks like is there a potential library version issue? I have copy pasted the proxy address as well. I have mcp with 1.9.2 version. I am working on course integrated notebook.

Error:

rror in /message route: Error: SSE connection not established
at SSEServerTransport.handlePostMessage (file:///home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/@modelcontextprotocol/sdk/dist/esm/server/sse.js:61:19)
at file:///home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/@modelcontextprotocol/inspector/server/build/index.js:262:25
at Layer.handleRequest (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/lib/layer.js:152:17)
at next (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/lib/route.js:157:13)
at Route.dispatch (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/lib/route.js:117:3)
at handle (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/index.js:435:11)
at Layer.handleRequest (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/lib/layer.js:152:17)
at /home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/index.js:295:15
at processParams (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/index.js:582:12)
at next (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/index.js:291:5)
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at new NodeError (node:internal/errors:405:5)
at ServerResponse.setHeader (node:_http_outgoing:648:11)
at ServerResponse.header (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/express/lib/response.js:684:10)
at ServerResponse.json (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/express/lib/response.js:247:10)
at file:///home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/@modelcontextprotocol/inspector/server/build/index.js:266:25
at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
Received message for sessionId c886b58d-a994-45c6-abaa-9e151e9cbe10
Error in /message route: Error: SSE connection not established
at SSEServerTransport.handlePostMessage (file:///home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/@modelcontextprotocol/sdk/dist/esm/server/sse.js:61:19)
at file:///home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/@modelcontextprotocol/inspector/server/build/index.js:262:25
at Layer.handleRequest (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/lib/layer.js:152:17)
at next (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/lib/route.js:157:13)
at Route.dispatch (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/lib/route.js:117:3)
at handle (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/index.js:435:11)
at Layer.handleRequest (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/lib/layer.js:152:17)
at /home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/index.js:295:15
at processParams (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/index.js:582:12)
at next (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/router/index.js:291:5)
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at new NodeError (node:internal/errors:405:5)
at ServerResponse.setHeader (node:_http_outgoing:648:11)
at ServerResponse.header (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/express/lib/response.js:684:10)
at ServerResponse.json (/home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/express/lib/response.js:247:10)
at file:///home/jovyan/.npm/_npx/5a9d879542beca3a/node_modules/@modelcontextprotocol/inspector/server/build/index.js:266:25
at process.processTicksAndRejections (node:internal/process/task_queues:95:5)

[TMosh]

Sorry, I am not a mentor for that course.

[lukmanaj]

It worked for me on the learning platform. I also got it to work locally. You can refresh and try again. Make sure you adjust all the configurations. In lesson 4, the connection was stdio and not sse.

[lukmanaj]

@Balaji.Illur I just tried it today and it worked. Just make sure you follow all the instructions exactly. The notebook way is just a workaround,as this should ideally be done locally. Hence, any missed step will prevent you inspector from connecting.

[encryptman]

Mine is also not working

[lukmanaj]

Not sure why it’s not working for you. But I suggest you try again one more time and see. It always works when I try on my end.