on Windows 10 with Python 3.8.2 and Python 3.9.0a4, the ProactorEventLoop raises "OSError: [WinError 87] The parameter is incorrect" when recvfrom on an AF_INET6 socket returns data:


DEBUG:asyncio:Using proactor: IocpProactor
INFO:asyncio:Datagram endpoint local_addr=('::', 11111) remote_addr=None created: (<_ProactorDatagramTransport fd=288>, <__main__.Prot object at 0x0000028739A09580>)
ERROR:root:error_received
Traceback (most recent call last):
  File "...\Python\Python39\lib\asyncio\proactor_events.py", line 548, in _loop_reading
    res = fut.result()
  File "...\Python\Python39\lib\asyncio\windows_events.py", line 808, in _poll
    value = callback(transferred, key, ov)
  File "...\Python\Python39\lib\asyncio\windows_events.py", line 496, in finish_recv
    return ov.getresult()
OSError: [WinError 87] The parameter is incorrect


The same code works without issues on python 3.7 or when using WindowsSelectorEventLoopPolicy.