MCP Server Initialization Error - 502 Bad Gateway when Connecting to SSE Server

[Yaozy-C]

Question:
When I run openai-agents-python sse example，some error happend. Can you tell me how to make it work properly?

Thanks

Environment:
Python version: 3.12
OS: macOS

openai-agents:0.0.7

tarting SSE server at http://localhost:8000/sse ...
INFO:     Started server process [72759]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://0.0.0.0:8000 (Press CTRL+C to quit)
SSE server started. Running example...


Error initializing MCP server: unhandled errors in a TaskGroup (1 sub-exception)
  + Exception Group Traceback (most recent call last):
  |   File "/Users/yaozy/PycharmProjects/mcp-demo/main.py", line 93, in <module>
  |     asyncio.run(main())
  |   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 194, in run
  |     return runner.run(main)
  |            ^^^^^^^^^^^^^^^^
  |   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 118, in run
  |     return self._loop.run_until_complete(task)
  |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/base_events.py", line 687, in run_until_complete
  |     return future.result()
  |            ^^^^^^^^^^^^^^^
  |   File "/Users/yaozy/PycharmProjects/mcp-demo/main.py", line 54, in main
  |     async with MCPServerSse(
  |                ^^^^^^^^^^^^^
  |   File "/Users/yaozy/PycharmProjects/mcp-demo/.venv/lib/python3.12/site-packages/agents/mcp/server.py", line 89, in __aenter__
  |     await self.connect()
  |   File "/Users/yaozy/PycharmProjects/mcp-demo/.venv/lib/python3.12/site-packages/agents/mcp/server.py", line 102, in connect
  |     transport = await self.exit_stack.enter_async_context(self.create_streams())
  |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/contextlib.py", line 659, in enter_async_context
  |     result = await _enter(cm)
  |              ^^^^^^^^^^^^^^^^
  |   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/contextlib.py", line 210, in __aenter__
  |     return await anext(self.gen)
  |            ^^^^^^^^^^^^^^^^^^^^^
  |   File "/Users/yaozy/PycharmProjects/mcp-demo/.venv/lib/python3.12/site-packages/mcp/client/sse.py", line 43, in sse_client
  |     async with anyio.create_task_group() as tg:
  |                ^^^^^^^^^^^^^^^^^^^^^^^^^
  |   File "/Users/yaozy/PycharmProjects/mcp-demo/.venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 772, in __aexit__
  |     raise BaseExceptionGroup(
  | ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)
  +-+---------------- 1 ----------------
    | Traceback (most recent call last):
    |   File "/Users/yaozy/PycharmProjects/mcp-demo/.venv/lib/python3.12/site-packages/mcp/client/sse.py", line 53, in sse_client
    |     event_source.response.raise_for_status()
    |   File "/Users/yaozy/PycharmProjects/mcp-demo/.venv/lib/python3.12/site-packages/httpx/_models.py", line 829, in raise_for_status
    |     raise HTTPStatusError(message, request=request, response=self)
    | httpx.HTTPStatusError: Server error '502 Bad Gateway' for url 'http://localhost:8000/sse'
For more information check: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/502
    +------------------------------------
INFO:     Shutting down
INFO:     Waiting for application shutdown.
INFO:     Application shutdown complete.
INFO:     Finished server process [72759]

[rm-openai]

Looks like the MCP server you started didn't actually start up correctly?

    | httpx.HTTPStatusError: Server error '502 Bad Gateway' for url 'http://localhost:8000/sse'

[Jedanny]

Same problem

[Yaozy-C]

I believe the MCP server is running correctly since I was able to access it through Google Chrome and received the expected response.
I used curl request MCP server，this is log:

curl -N -H "Accept: text/event-stream" http://127.0.0.1:8000/sse
event: endpoint
data: /messages/?session_id=dd4e96671fc94fec8832a522a3222e5d

[Jedanny]

I believe the MCP server is running correctly since I was able to access it through Google Chrome and received the expected response. I used curl request MCP server，this is log:

curl -N -H "Accept: text/event-stream" http://127.0.0.1:8000/sse
event: endpoint
data: /messages/?session_id=dd4e96671fc94fec8832a522a3222e5d

Check whether the network proxy is turned on, my local network proxy is normal when it is turned off, and it is estimated that the httpx and mcp.sse implementation is related

[Yaozy-C]

I believe the MCP server is running correctly since I was able to access it through Google Chrome and received the expected response. I used curl request MCP server，this is log:

curl -N -H "Accept: text/event-stream" http://127.0.0.1:8000/sse
event: endpoint
data: /messages/?session_id=dd4e96671fc94fec8832a522a3222e5d

Check whether the network proxy is turned on, my local network proxy is normal when it is turned off, and it is estimated that the httpx and mcp.sse implementation is related

It‘s work！Thanks

[rm-openai]

Thanks @Jedanny! Closing this out.