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Author kbr
Recipients asvetlov, kbr, yselivanov
Date 2020-03-22.09:59:41
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Marked as misclassified Yes
Message-id <>
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>)
Traceback (most recent call last):
  File "...\Python\Python39\lib\asyncio\", line 548, in _loop_reading
    res = fut.result()
  File "...\Python\Python39\lib\asyncio\", line 808, in _poll
    value = callback(transferred, key, ov)
  File "...\Python\Python39\lib\asyncio\", 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.
Date User Action Args
2020-03-22 09:59:42kbrsetrecipients: + kbr, asvetlov, yselivanov
2020-03-22 09:59:42kbrsetmessageid: <>
2020-03-22 09:59:42kbrlinkissue40040 messages
2020-03-22 09:59:41kbrcreate