[aiohttp.server] Error handling request URLError: 400, message='invalid URL'

Configuration
1

In my log I am starting to see these lines:

2021-06-02 10:49:24 ERROR (MainThread) [aiohttp.server] Error handling request
Traceback (most recent call last):
  File "/srv/homeassistant/lib/python3.8/site-packages/aiohttp/web_protocol.py", line 314, in data_received
    messages, upgraded, tail = self._request_parser.feed_data(data)
  File "aiohttp/_http_parser.pyx", line 546, in aiohttp._http_parser.HttpParser.feed_data
aiohttp.http_exceptions.BadHttpMessage: 400, message='invalid constant string'
2021-06-02 10:49:29 ERROR (MainThread) [aiohttp.server] Error handling request
Traceback (most recent call last):
  File "/srv/homeassistant/lib/python3.8/site-packages/aiohttp/web_protocol.py", line 314, in data_received
    messages, upgraded, tail = self._request_parser.feed_data(data)
  File "aiohttp/_http_parser.pyx", line 546, in aiohttp._http_parser.HttpParser.feed_data
aiohttp.http_exceptions.BadStatusLine: 400, message="Bad status line 'invalid HTTP method'"

I am not sure where they come from: I don’t see any component name, so I don’t know where to start.
HA Core 2021.5.5.

Thanks

2

Plenty of those as well, and I’m clueless as well :wink:
I don’t even know how to start debugging the cause.