AttributeError: type object 'async_generator_asend' has no attribute 'f_lineno' #699

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1. gloryfromca commented on Nov 4, 2025

   

   gloryfromca

   on Nov 4, 2025

   Last edited by gloryfromca

   More actions

   same question.

   • reproduce code

   # main.py
   import uvicorn
   from fastapi import FastAPI, Request
   from starlette.middleware.base import BaseHTTPMiddleware
   from starlette.responses import JSONResponse
   
   app = FastAPI()
   
   # Define three simple middlewares. The third one will try to read the request body.
   class FirstMiddleware(BaseHTTPMiddleware):
       async def dispatch(self, request: Request, call_next):
           print("Entering First Middleware")
           response = await call_next(request)
           print("Exiting First Middleware")
           return response
   
   class SecondMiddleware(BaseHTTPMiddleware):
       async def dispatch(self, request: Request, call_next):
           print("Entering Second Middleware")
           response = await call_next(request)
           print("Exiting Second Middleware")
           return response
   
   class ThirdMiddleware(BaseHTTPMiddleware):
       async def dispatch(self, request: Request, call_next):
           response = await call_next(request)
           return response
   
   
   # Add the three middlewares to the application
   app.add_middleware(FirstMiddleware)
   app.add_middleware(SecondMiddleware)
   app.add_middleware(ThirdMiddleware) # <-- If you comment out this line, or any of the others, the error disappears.
   
   @app.post("/test")
   async def test_endpoint(request: Request):
       # The endpoint can also try to access the body, which still works
       # because BaseHTTPMiddleware caches it.
       body = await request.json()
       return JSONResponse({"message": "success", "body_received": body})
   
   if __name__ == "__main__":
       uvicorn.run(app, host="0.0.0.0", port=8090)
   

   • .env

   PYTHONASYNCIODEBUG=1
   

   Error

   Exception ignored in: <async_generator object Request.stream at 0x106c97680>
   Traceback (most recent call last):
     File "uvloop/loop.pyx", line 3187, in uvloop.loop.Loop._asyncgen_finalizer_hook
     File "uvloop/loop.pyx", line 1289, in uvloop.loop.Loop.call_soon_threadsafe
     File "uvloop/cbhandles.pyx", line 329, in uvloop.loop.new_Handle
     File "uvloop/cbhandles.pyx", line 15, in uvloop.loop.Handle._set_loop
     File "uvloop/cbhandles.pyx", line 427, in uvloop.loop.extract_stack
     File "/Users/admin/miniconda3/envs/py312/lib/python3.12/traceback.py", line 395, in extract
       return klass._extract_from_extended_frame_gen(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     File "/Users/admin/miniconda3/envs/py312/lib/python3.12/traceback.py", line 418, in _extract_from_extended_frame_gen
       for f, (lineno, end_lineno, colno, end_colno) in frame_gen:
                                                        ^^^^^^^^^
     File "/Users/admin/miniconda3/envs/py312/lib/python3.12/traceback.py", line 392, in extended_frame_gen
       for f, lineno in frame_gen:
                        ^^^^^^^^^
     File "/Users/admin/miniconda3/envs/py312/lib/python3.12/traceback.py", line 336, in walk_stack
       yield f, f.f_lineno
                ^^^^^^^^^^
   AttributeError: type object 'StopIteration' has no attribute 'f_lineno'
   
2. alexliyu7352

   added a commit that references this issue on Sep 14, 2026

   ci: make the Redis integration tests self-contained and fix the CI en…

   ...

   1ee7ddd