bpo-33981 has been marked as a duplicate of this issue. Copy of messages:

msg320583 - (view) 	Author: STINNER Victor (vstinner) * (Python committer) 	Date: 2018-06-27 14:26

Python 3.8 (master) on Windows 10:

C:\vstinner\python\master>python -m test test_asyncio -m test_sendfile_close_peer_in_the_middle_of_receiving -v
Running Debug|x64 interpreter...
== CPython 3.8.0a0 (heads/wip:dd08b85c84, Jun 26 2018, 12:47:56) [MSC v.1914 64 bit (AMD64)]
== Windows-10-10.0.16299-SP0 little-endian
== cwd: C:\vstinner\python\master\build\test_python_7020
== CPU count: 2
== encodings: locale=cp1252, FS=utf-8
Run tests sequentially
0:00:00 [1/1] test_asyncio
test_sendfile_close_peer_in_the_middle_of_receiving (test.test_asyncio.test_events.ProactorEventLoopTests) ... Exception in callback _ProactorReadPipeTransport._loop_reading(<_OverlappedF...ne, 64, None)>)
handle: <Handle _ProactorReadPipeTransport._loop_reading(<_OverlappedF...ne, 64, None)>)>
Traceback (most recent call last):
  File "C:\vstinner\python\master\lib\asyncio\windows_events.py", line 428, in finish_recv
    return ov.getresult()
OSError: [WinError 64] The specified network name is no longer available

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\vstinner\python\master\lib\asyncio\proactor_events.py", line 255, in _loop_reading
    data = fut.result()
  File "C:\vstinner\python\master\lib\asyncio\windows_events.py", line 732, in _poll
    value = callback(transferred, key, ov)
  File "C:\vstinner\python\master\lib\asyncio\windows_events.py", line 432, in finish_recv
    raise ConnectionResetError(*exc.args)
ConnectionResetError: [WinError 64] The specified network name is no longer available

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\vstinner\python\master\lib\asyncio\events.py", line 88, in _run
    self._context.run(self._callback, *self._args)
  File "C:\vstinner\python\master\lib\asyncio\proactor_events.py", line 282, in _loop_reading
    self._force_close(exc)
  File "C:\vstinner\python\master\lib\asyncio\proactor_events.py", line 117, in _force_close
    self._empty_waiter.set_exception(exc)
concurrent.futures._base.InvalidStateError: invalid state
ok
test_sendfile_close_peer_in_the_middle_of_receiving (test.test_asyncio.test_events.SelectEventLoopTests) ... ok

----------------------------------------------------------------------
Ran 2 tests in 0.111s

OK

== Tests result: SUCCESS ==

1 test OK.

Total duration: 453 ms
Tests result: SUCCESS

msg320586 - (view) 	Author: STINNER Victor (vstinner) * (Python committer) 	Date: 2018-06-27 14:30

See also bpo-32710: "test_asyncio leaked [4, 4, 3] memory blocks, sum=11 on AMD64 Windows8.1 Refleaks 3.x".

msg320587 - (view) 	Author: STINNER Victor (vstinner) * (Python committer) 	Date: 2018-06-27 14:31

Oh, it's a duplicate of bpo-33834.