HTTPProxyActor Invalid HTTP request received. illegal request line: bytearray(b'SM')

Came at some point into HTTPProxyActor log. The log line has no timestamp… I don’t know the call that was made. However, my question is does anyone know what could cause this error?

Traceback

Traceback (most recent call last):
--
  | File "/usr/local/lib/python3.10/site-packages/uvicorn/protocols/http/h11_impl.py", line 136, in handle_events
  | event = self.conn.next_event()
  | File "/usr/local/lib/python3.10/site-packages/h11/_connection.py", line 485, in next_event
  | exc._reraise_as_remote_protocol_error()
  | File "/usr/local/lib/python3.10/site-packages/h11/_util.py", line 77, in _reraise_as_remote_protocol_error
  | raise self
  | File "/usr/local/lib/python3.10/site-packages/h11/_connection.py", line 467, in next_event
  | event = self._extract_next_receive_event()
  | File "/usr/local/lib/python3.10/site-packages/h11/_connection.py", line 409, in _extract_next_receive_event
  | event = self._reader(self._receive_buffer)
  | File "/usr/local/lib/python3.10/site-packages/h11/_readers.py", line 81, in maybe_read_from_IDLE_client
  | raise LocalProtocolError("illegal request line")
  | h11._util.RemoteProtocolError: illegal request line
  | WARNING:  Invalid HTTP request received.
  | Traceback (most recent call last):
  | File "/usr/local/lib/python3.10/site-packages/uvicorn/protocols/http/h11_impl.py", line 136, in handle_events
  | event = self.conn.next_event()
  | File "/usr/local/lib/python3.10/site-packages/h11/_connection.py", line 485, in next_event
  | exc._reraise_as_remote_protocol_error()
  | File "/usr/local/lib/python3.10/site-packages/h11/_util.py", line 77, in _reraise_as_remote_protocol_error
  | raise self
  | File "/usr/local/lib/python3.10/site-packages/h11/_connection.py", line 467, in next_event
  | event = self._extract_next_receive_event()
  | File "/usr/local/lib/python3.10/site-packages/h11/_connection.py", line 409, in _extract_next_receive_event
  | event = self._reader(self._receive_buffer)
  | File "/usr/local/lib/python3.10/site-packages/h11/_readers.py", line 85, in maybe_read_from_IDLE_client
  | matches = validate(
  | File "/usr/local/lib/python3.10/site-packages/h11/_util.py", line 91, in validate
  | raise LocalProtocolError(msg)
  | h11._util.RemoteProtocolError: illegal request line: bytearray(b'SM')
  | WARNING:  Invalid HTTP request received.

Update:

maybe this comment on SO is relevent.

My issue was that when I was calling my FastAPI microservice I was using https when my microservice did not have HTTPS support. I changed the url from https to http and it started working as expected.
Note that if your service requires HTTPS support you can add HTTPS support as Ilgizar Murzakov suggests.

Did the comment help? Did changing from https to http make the error go away?