[Bug] RuntimeError: Received request before initialization was complete

What happened?

模型是本地 vllm启动的 Qwen2.5-7B-Instruct
客户端是 cherry studio
调用 WAF的mcp功能时，后台出现以下报错：
INFO: 192.168.191.136:11116 - "POST /messages/?session_id=4f90997c0636401dbd7debe48ca6d9b9 HTTP/1.1" 202 Accepted

ERROR: Exception in ASGI application

• Exception Group Traceback (most recent call last):

| File "/usr/local/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 "/usr/local/lib/python3.13/site-packages/uvicorn/middleware/proxy_headers.py", line 60, in call

| return await self.app(scope, receive, send)

| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

| File "/usr/local/lib/python3.13/site-packages/starlette/applications.py", line 112, in call

| await self.middleware_stack(scope, receive, send)

| File "/usr/local/lib/python3.13/site-packages/starlette/middleware/errors.py", line 187, in call

| raise exc

| File "/usr/local/lib/python3.13/site-packages/starlette/middleware/errors.py", line 165, in call

| await self.app(scope, receive, _send)

| File "/usr/local/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 "/usr/local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app

| raise exc

| File "/usr/local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app

| await app(scope, receive, sender)

| File "/usr/local/lib/python3.13/site-packages/starlette/routing.py", line 714, in call

| await self.middleware_stack(scope, receive, send)

| File "/usr/local/lib/python3.13/site-packages/starlette/routing.py", line 734, in app

| await route.handle(scope, receive, send)

| File "/usr/local/lib/python3.13/site-packages/starlette/routing.py", line 288, in handle

| await self.app(scope, receive, send)

| File "/usr/local/lib/python3.13/site-packages/starlette/routing.py", line 76, in app

| await wrap_app_handling_exceptions(app, request)(scope, receive, send)

| File "/usr/local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app

| raise exc

| File "/usr/local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app

| await app(scope, receive, sender)

| File "/usr/local/lib/python3.13/site-packages/starlette/routing.py", line 73, in app

| response = await f(request)

| ^^^^^^^^^^^^^^^^

| File "/app/server.py", line 33, in handle_sse

| async with sse.connect_sse(

| ~~~~~~~~~~~~~~~^

| request.scope, request.receive, request._send

| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

| ) as [read_stream, write_stream]:



^

| File "/usr/local/lib/python3.13/contextlib.py", line 235, in aexit

| await self.gen.athrow(value)

| File "/usr/local/lib/python3.13/site-packages/mcp/server/sse.py", line 123, in connect_sse

| async with anyio.create_task_group() as tg:

| ~~~~~~~~~~~~~~~~~~~~~~~^^

| File "/usr/local/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 "/usr/local/lib/python3.13/site-packages/mcp/server/sse.py", line 131, in connect_sse

|     yield (read_stream, write_stream)

|   File "/app/server.py", line 36, in handle_sse

|     await mcp_server.run(

|         read_stream, write_stream, mcp_server.create_initialization_options()

|     )

|   File "/usr/local/lib/python3.13/site-packages/mcp/server/lowlevel/server.py", line 483, in run

|     async with AsyncExitStack() as stack:

|                ~~~~~~~~~~~~~~^^

|   File "/usr/local/lib/python3.13/contextlib.py", line 768, in __aexit__

|     raise exc

|   File "/usr/local/lib/python3.13/contextlib.py", line 751, in __aexit__

|     cb_suppress = await cb(*exc_details)

|                   ^^^^^^^^^^^^^^^^^^^^^^

|   File "/usr/local/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 "/usr/local/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 "/usr/local/lib/python3.13/site-packages/mcp/shared/session.py", line 324, in _receive_loop

  |     await self._received_request(responder)

  |   File "/usr/local/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

  +------------------------------------

How we reproduce?

1. ...
2. ...
3. ...

Expected behavior

No response

Error log

No response

Start with the /app/server.py handle_sse entry point and the MCP server run call shown in the traceback, then trace the session initialization flow in the reported MCP components. Reproduce the Cherry Studio and local vLLM Qwen2.5-7B-Instruct setup; done means requests no longer arrive before initialization completes and the reported exception is covered by a reliable reproduction or test.