AttributeError: 'NoneType' object has no attribute 'cancelled'

• asyncpg version: 0.14.0
• PostgreSQL version: 9.6.6
• Do you use a PostgreSQL SaaS? If so, which? Can you reproduce the issue with a local PostgreSQL install?: I can’t reproduce
• Python version: 3.6.4
• Platform: Alpine Linux
• Do you use pgbouncer?: Yes
• Did you install asyncpg with pip?: Yes
• If you built asyncpg locally, which version of Cython did you use?: 0.27.3
• Can the issue be reproduced under both asyncio and uvloop?: No

Same query sometimes breaks with this, meaning the exact query other times works flawlessly, any ideas?

[06:06:23][ERROR] robbie.http.microservice.middleware.errors api.py:__call__:242 | ("Non SQL error happened: 'NoneType' object has no attribute 'cancelled'", AttributeError("'NoneType' object has no attribute 'cancelled'",))
Traceback (most recent call last):
  File "robbie/sql/postgresql/utils.py", line 119, in robbie.sql.postgresql.utils.sql_exceptions_handler.wrapper
  File "robbie/sql/postgresql/client.py", line 119, in fetch
  File "/usr/local/lib/python3.6/site-packages/asyncpg/pool.py", line 405, in fetch
    return await con.fetch(query, *args, timeout=timeout)
  File "/usr/local/lib/python3.6/site-packages/asyncpg/connection.py", line 345, in fetch
    return await self._execute(query, args, 0, timeout)
  File "/usr/local/lib/python3.6/site-packages/asyncpg/connection.py", line 1289, in _execute
    query, args, limit, timeout, return_status=return_status)
  File "/usr/local/lib/python3.6/site-packages/asyncpg/connection.py", line 1297, in __execute
    return await self._do_execute(query, executor, timeout)
  File "/usr/local/lib/python3.6/site-packages/asyncpg/connection.py", line 1312, in _do_execute
    stmt = await self._get_statement(query, timeout)
  File "/usr/local/lib/python3.6/site-packages/asyncpg/connection.py", line 286, in _get_statement
    statement = await self._protocol.prepare(stmt_name, query, timeout)
  File "asyncpg/protocol/protocol.pyx", line 168, in prepare
  File "asyncpg/protocol/coreproto.pyx", line 122, in asyncpg.protocol.protocol.CoreProtocol._read_server_messages
  File "asyncpg/protocol/coreproto.pyx", line 625, in asyncpg.protocol.protocol.CoreProtocol._push_result
  File "asyncpg/protocol/protocol.pyx", line 818, in asyncpg.protocol.protocol.BaseProtocol._on_result
  File "asyncpg/protocol/protocol.pyx", line 745, in asyncpg.protocol.protocol.BaseProtocol._dispatch_result
AttributeError: 'NoneType' object has no attribute 'cancelled'

[thehesiod]

I just hit this w/ copy_from_query and it reminded me of https://github.com/MagicStack/asyncpg/issues/726 (which is an asyncio bug), so I tried w/ uvloop and that seems to fix the problem as well.

[yohanboniface]

FYI, I have the same issue (using copy_from_table) on a server running python 3.8, but not in local running python 3.9 or 3.10. And I confirm that using uvloop works around the issue.