Python Bug: Error while trying to interact with the MCP server

[Javipercor]

Describe the bug
While trying to interact with the MCP Server (python/samples/demos/mcp_server/agent_as_server.py) The server breaks with POST request to list the tools and also to interact with the one available.

ERROR: Exception in ASGI application

• Exception Group Traceback (most recent call last):
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/uvicorn/protocols/http/h11_impl.py", line 403, in run_asgi
  | result = await app( # type: ignore[func-returns-value]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  | self.scope, self.receive, self.send
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  | )
  | ^
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/uvicorn/middleware/proxy_headers.py", line 60, in call
  | return await self.app(scope, receive, send)
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/applications.py", line 112, in call
  | await self.middleware_stack(scope, receive, send)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/middleware/errors.py", line 187, in call
  | raise exc
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/middleware/errors.py", line 165, in call
  | await self.app(scope, receive, _send)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/middleware/exceptions.py", line 62, in call
  | await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
  | raise exc
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
  | await app(scope, receive, sender)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/routing.py", line 714, in call
  | await self.middleware_stack(scope, receive, send)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/routing.py", line 734, in app
  | await route.handle(scope, receive, send)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/routing.py", line 288, in handle
  | await self.app(scope, receive, send)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/routing.py", line 76, in app
  | await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
  | raise exc
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
  | await app(scope, receive, sender)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/starlette/routing.py", line 73, in app
  | response = await f(request)
  | ^^^^^^^^^^^^^^^^
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/agent_as_server.py", line 120, in handle_sse
  | async with sse.connect_sse(request.scope, request.receive, request._send) as (
  | ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  | File "/opt/homebrew/Cellar/python@3.13/3.13.2/Frameworks/Python.framework/Versions/3.13/lib/python3.13/contextlib.py", line 235, in aexit
  | await self.gen.athrow(value)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/mcp/server/sse.py", line 123, in connect_sse
  | async with anyio.create_task_group() as tg:
  | ~~~~~~~~~~~~~~~~~~~~~~~^^
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/anyio/_backends/_asyncio.py", line 772, in aexit
  | raise BaseExceptionGroup(
  | "unhandled errors in a TaskGroup", self._exceptions
  | ) from None
  | ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)
  +-+---------------- 1 ----------------
  | Exception Group Traceback (most recent call last):
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/mcp/server/sse.py", line 131, in connect_sse
  | yield (read_stream, write_stream)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/agent_as_server.py", line 124, in handle_sse
  | await server.run(read_stream, write_stream, server.create_initialization_options())
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/mcp/server/lowlevel/server.py", line 483, in run
  | async with AsyncExitStack() as stack:
  | ~~~~~~~~~~~~~~^^
  | File "/opt/homebrew/Cellar/python@3.13/3.13.2/Frameworks/Python.framework/Versions/3.13/lib/python3.13/contextlib.py", line 768, in aexit
  | raise exc
  | File "/opt/homebrew/Cellar/python@3.13/3.13.2/Frameworks/Python.framework/Versions/3.13/lib/python3.13/contextlib.py", line 751, in aexit
  | cb_suppress = await cb(*exc_details)
  | ^^^^^^^^^^^^^^^^^^^^^^
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/mcp/shared/session.py", line 210, in aexit
  | return await self._task_group.aexit(exc_type, exc_val, exc_tb)
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/anyio/_backends/_asyncio.py", line 772, in aexit
  | raise BaseExceptionGroup(
  | "unhandled errors in a TaskGroup", self._exceptions
  | ) from None
  | ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)
  +-+---------------- 1 ----------------
  | Traceback (most recent call last):
  | File "/opt/homebrew/Cellar/python@3.13/3.13.2/Frameworks/Python.framework/Versions/3.13/lib/python3.13/asyncio/tasks.py", line 304, in __step_run_and_handle_result
  | result = coro.send(None)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/mcp/shared/session.py", line 324, in _receive_loop
  | await self._received_request(responder)
  | File "/Users/javipercor/Development/semantic-kernel-mod/python/samples/demos/mcp_server/.venv/lib/python3.13/site-packages/mcp/server/session.py", line 163, in _received_request
  | raise RuntimeError(
  | "Received request before initialization was complete"
  | )
  | RuntimeError: Received request before initialization was complete
  +------------------------------------

To Reproduce
Steps to reproduce the behavior:

1. Go to python/samples/demos/mcp_server/agent_as_server.py
2. Execute script with see flag and port 8000
3. Send GET request to generate session in MCP
4. Send POST request to initialize
   {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"MCPClientPoc","version":"1.0.0.0"}},"id":1,"jsonrpc":"2.0"}
5. Send POST request to list tools
   {"method":"tools/list","params":{},"id":1,"jsonrpc":"2.0"}

Expected behavior
Error as the stated in the description will arise

Screenshots
If applicable, add screenshots to help explain your problem.

Platform

• Language: Python
• Source: Semantic-kernel 1.28.1
• AI model: Azure OpenAI GPT-4o(2024-07-18)]
• IDE: VS Code
• OS: MAC

Temporary Solution

Surfing the web I found that a working patch could be to add the following code after the package imports:

#PATCH
from mcp.server.session import ServerSession

old__received_request = ServerSession._received_request

async def _received_request(self, *args, **kwargs):
try:
return await old__received_request(self, *args, **kwargs)
except RuntimeError:
pass

ServerSession._received_request = _received_request

[eavanvalkenburg]

@Javipercor if I read the last part correctly, this is a bug in the MCP package or not?

[Javipercor]

yes, it is.
Maybe if it is a third party bug, that make a execution breaking impact on semantic kernel, the label of the issue has to be different, or the way to report it?

[eavanvalkenburg]

Could it be this one? modelcontextprotocol/python-sdk#583

[Javipercor]

Don´t think so, more about this open discussion https://github.com/orgs/modelcontextprotocol/discussions/266

[moonbox3]

@Javipercor, with the latest SK 1.31.0 do you still experience an issue?