401 unauthorized on simple-auth example

[luarss]

Describe the bug
Unable to get access to MCP server

To Reproduce
Followed all instructions in https://github.com/modelcontextprotocol/python-sdk/tree/main/examples/servers/simple-auth

Expected behavior
Using mcp-inspector, gotten 401 error when connecting via http://localhost:8000/sse

SSE transport: url=http://localhost:8000/sse, headers=Accept
Received 401 Unauthorized from MCP server: SSE error: Non-200 status code (401)

Please let me know if any information is needed

[ihrpr]

@luarss please can you share server logs?

[luarss]

Hi @ihrpr, logs as follows.

Here is my oauth app config

MCP inspector config

[luarss]

Hi @ihrpr found the regression lies actually in mcp-inspector client, not the code.

Code example works with npx @modelcontextprotocol/inspector@0.11.0. Perhaps we could add that blurb while they fix the issue?

modelcontextprotocol/inspector#390

[ihrpr]

Thank you, looking into it!

[bttopfer]

I ran into the same issue - using inspector@0.11.0 does not help. Using /mcp - so streamable http transport.
Authentication works fine when I run with custom test script (initialize, initialized.....), but fails with 401 in inspector and I do not even get to my implementation of OAuthAuthorizationServerProvider ( no logs for e.g. load_access_token). If I disable auth it works fine.

[zackify]

Yeah it’s really really annoying they don’t release the new update.

But you can work around it like I have.

Use v11 and select SSE. Then hit connect.

Oauth.

Now once oauth is successful. You start v12 and switch to streamable http because only v12 sends the header there 😆😆

Or everyone is just using provider specific cloudflare tooling right now.