Running Simple Auth Github Example throws 404 error #679

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1. lukekulik commented on May 12, 2025

   

   lukekulik

   on May 12, 2025

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   I'm running into the same issue, could one of the maintainers take a look?
2. ihrpr

   self-assigned this

   on May 13, 2025
3. ihrpr commented on May 17, 2025

   

   ihrpr

   on May 17, 2025

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   @mopg have you tried running with inspector?

   Please can you share the parameters you are using to set up the server?
4. mopg commented on May 17, 2025

   

   mopg

   on May 17, 2025

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   Thanks for help, @ihrpr!

   So with inspector, I'm now getting the following (also using the latest server.py from a few days ago) (so 401 instead of 404):

   New SSE connection. NOTE: The sse transport is deprecated and has been replaced by streamable-http
   Query parameters: [Object: null prototype] {
     url: 'http://localhost:8000/sse',
     transportType: 'sse'
   }
   SSE transport: url=http://localhost:8000/sse, headers=Accept
   Received 401 Unauthorized from MCP server: SSE error: Non-200 status code (401)
   

   And on the server logs

   INFO:     Started server process [27494]
   INFO:     Waiting for application startup.
   INFO:     Application startup complete.
   INFO:     Uvicorn running on http://localhost:8000 (Press CTRL+C to quit)
   INFO:     ::1:61155 - "GET /sse HTTP/1.1" 401 Unauthorized
   INFO:     ::1:61195 - "GET /sse HTTP/1.1" 401 Unauthorized
   

   I get this after clicking "Connect" with the parameters below in the inspector.
   

   I ran the inspector using npx @modelcontextprotocol/inspector uv run mcp-simple-auth

   This is all using version mcp==1.9.0.
5. ihrpr commented on May 19, 2025

   

   ihrpr

   on May 19, 2025

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   thanks, there is Inspector issues we are looking at now: modelcontextprotocol/inspector#390
6. mopg commented on May 19, 2025

   

   mopg

   on May 19, 2025

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   Eh ok, seeing the inspector issues indeed. But I'm still getting this 401 error also when using Claude Code. So that seems to be unrelated for this particular issue.

   @ihrpr are you able to run the example without any problems then? (Just in Claude, Cursor, wherever)
7. ihrpr commented on May 19, 2025

   

   ihrpr

   on May 19, 2025

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   @ihrpr are you able to run the example without any problems then? (Just in Claude, Cursor, wherever)

   yes, I can run with test clients as well as now with inspector (after the inspector fix)

   Have you made any change to the server?
8. RamyaPrasad24 commented on May 20, 2025

   

   RamyaPrasad24

   on May 20, 2025

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   I initially faced the same issue, now able to run with inspector.
   Thanks for the fix!
   However, I am now encountering a new issue with my simple client setup to communicate with the server

   httpx.HTTPStatusError: Client error '401 Unauthorized' for url 'http://localhost:8000/sse' error

   My client code :

   from mcp import ClientSession
   from mcp.client.sse import sse_client
   import anyio
   from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
   from mcp.shared.message import SessionMessage
   from mcp.shared.session import RequestResponder
   import mcp.types as types
   import argparse
   import logging
   import sys
   from functools import partial
   from urllib.parse import urlparse
   
   if not sys.warnoptions:
       import warnings
   
       warnings.simplefilter("ignore")
   
   logging.basicConfig(level=logging.INFO)
   logger = logging.getLogger("client")
   
   async def message_handler(
       message: RequestResponder[types.ServerRequest, types.ClientResult]
       | types.ServerNotification
       | Exception,
   ) -> None:
       if isinstance(message, Exception):
           logger.error("Error: %s", message)
           return
   
       logger.info("Received message from server: %s", message)
   
   async def run_session(
       read_stream: MemoryObjectReceiveStream[SessionMessage | Exception],
       write_stream: MemoryObjectSendStream[SessionMessage],
       client_info: types.Implementation | None = None,
   ):
       async with ClientSession(
           read_stream,
           write_stream,
           message_handler=message_handler,
           client_info=client_info,
       ) as session:
           logger.info("Initializing session")
           await session.initialize()
           logger.info("Initialized")
         
   async def main():
       async with sse_client("http://localhost:8000/sse") as (
           read_stream,
           write_stream,
           _,
       ):
           # Create a session using the client streams
           async with ClientSession(read_stream, write_stream) as session:
               # Initialize the connection
               await session.initialize()
               # List available tools
               tools = await session.list_tools()
               print("Available Tools:", tools)
               # Call a tool
               tool_result = await session.call_tool("get_user_profile")
   
   if __name__ == "__main__":
       anyio.run(main)
   

   @ihrpr Could you please assist in resolving this error? Any guidance on how to handle authentication or properly configure my client would be greatly appreciated.

   Thank you!
9. felixweinberger commented on Oct 3, 2025

   

   felixweinberger

   on Oct 3, 2025

   Contributor

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   Closing as initial inspector issue has been resolved.

   If there's still an issue you're facing please feel free to reopen or open a new one with the detailed repro!
10. felixweinberger

    closed this as completedon Oct 3, 2025
11. felixweinberger

    added

    bugSomething isn't workingSomething isn't working

    authIssues and PRs related to Authentication / OAuthIssues and PRs related to Authentication / OAuth

    on Oct 3, 2025