Stuck with: WARNING: Invalid HTTP request received.

Hi there,

I’m using FastAPI with uvicorn and I’m running into an issue which I’m not sure how to debug/solve. I wasn’t sure where to post this, but since the error message comes from uvicorn I decided to post it here.

There is no issue if I send a single GET request:

DEBUG: ('10.144.0.115', 48348) - Connected
DEBUG: ('10.144.0.115', 48348) - ASGI [48] Started
DEBUG: ('10.144.0.115', 48348) - ASGI [48] Received {'type': 'http.response.start', 'status': 200, 'headers': '<...>'}
INFO: ('10.144.0.115', 48348) - "GET /charts HTTP/1.1" 200
DEBUG: ('10.144.0.115', 48348) - ASGI [48] Received {'type': 'http.response.body', 'body': '<41112 bytes>'}
DEBUG: ('10.144.0.115', 48348) - ASGI [48] Completed
DEBUG: ('10.144.0.115', 48348) - Disconnected

But if I send a second GET request while the connection from the first request is still open I get WARNING: Invalid HTTP request received.. Here is the complete log for the two requests:

DEBUG: ('10.144.0.115', 49422) - Connected
DEBUG: ('10.144.0.115', 49422) - ASGI [51] Started
DEBUG: ('10.144.0.115', 49422) - ASGI [51] Received {'type': 'http.response.start', 'status': 200, 'headers': '<...>'}
INFO: ('10.144.0.115', 49422) - "GET /charts HTTP/1.1" 200
DEBUG: ('10.144.0.115', 49422) - ASGI [51] Received {'type': 'http.response.body', 'body': '<41112 bytes>'}
DEBUG: ('10.144.0.115', 49422) - ASGI [51] Completed
WARNING: Invalid HTTP request received.
DEBUG: ('10.144.0.115', 49422) - Disconnected
DEBUG: ('10.144.0.115', 49430) - Connected
DEBUG: ('10.144.0.115', 49430) - ASGI [52] Started
DEBUG: ('10.144.0.115', 49430) - ASGI [52] Received {'type': 'http.response.start', 'status': 200, 'headers': '<...>'}
INFO: ('10.144.0.115', 49430) - "GET /charts HTTP/1.1" 200
DEBUG: ('10.144.0.115', 49430) - ASGI [52] Received {'type': 'http.response.body', 'body': '<41112 bytes>'}
DEBUG: ('10.144.0.115', 49430) - ASGI [52] Completed
DEBUG: ('10.144.0.115', 49430) - Disconnected

This isn’t too bad, because I still receive the responses for each request, even with the warning.

But if I try to send a POST request from a react-frontend it gets worse. The POST request from the frontend comes with a Preflight OPTIONS request. That means if I hit the send-button in the frontend the browser sends an OPTIONS request immediately followed by a POST request.

The server log looks like this:

DEBUG: ('10.144.0.115', 44982) - Connected
DEBUG: ('10.144.0.115', 44982) - ASGI [14] Started
DEBUG: ('10.144.0.115', 44982) - ASGI [14] Received {'type': 'http.response.start', 'status': 200, 'headers': '<...>'}
INFO: ('10.144.0.115', 44982) - "OPTIONS /colors HTTP/1.1" 200
DEBUG: ('10.144.0.115', 44982) - ASGI [14] Received {'type': 'http.response.body', 'body': '<2 bytes>'}
DEBUG: ('10.144.0.115', 44982) - ASGI [14] Completed
WARNING: Invalid HTTP request received.
DEBUG: ('10.144.0.115', 44982) - Disconnected

The OPTIONS request gets through, but the POST request doesn’t. The payload from the frontend doesn’t reach the backend.

Now the strangest thing: If I hammer the send-button multiple times a second, the POST request will get through eventually.

Does anyone know what’s going on or how this could be solved?

[reminizdeveloper]

Hi there, I do have the same issue but I can’t replicate it locally, I only see it on a deployed kubernetes cluster.

I am using gunicorn and the issue disappear if I switch from uvicorn.workers.UvicornWorker to uvicorn.workers.UvicornH11Worker.

It seems related to #344

[jlienSage]

@euri10 Just rebuilt our image using latest base image. Uvicorn is 0.11.3 and gunicorn is 20.0.4.

The issue persists when we turn on CORS and Azure inserts its middleware to handle CORS.

Update: @euri10 Adding the following environment variable is a work-around for this issue: GUNICORN_CMD_ARGS="--keep-alive 0"