connection.close is throwing protocol error

[immohsin]

asyncpg version: 0.18.1
PostgreSQL version: 9.5.10
Do you use a PostgreSQL SaaS? If so, which? Can you reproduce
the issue with a local PostgreSQL install?: using google cloud sql pg instance
Python version: 3.6.5
Platform: Ubuntu
Do you use pgbouncer?: No
Did you install asyncpg with pip?: Yes
If you built asyncpg locally, which version of Cython did you use?:
Can the issue be reproduced under both asyncio and
uvloop?: No

I have been facing this error for quite sometime intermittently asyncpg.exceptions._base.InternalClientError: got result for unknown protocol state 0

The entire stack trace:

 File "/repo/server/schema_db.py", line 345, in read
    await connection.close()

  File "/usr/local/lib/python3.6/dist-packages/asyncpg/connection.py", line 1082, in close
    await self._protocol.close(timeout)

  File "asyncpg/protocol/protocol.pyx", line 560, in close

  File "asyncpg/protocol/protocol.pyx", line 814, in asyncpg.protocol.protocol.BaseProtocol._dispatch_result

asyncpg.exceptions._base.InternalClientError: got result for unknown protocol state 0

Can someone explain when this exception is thrown and for what reason?
If i know the reason this exception is thrown, i can figure out the issue myself.
I'm not able to reproduce locally or in my stage environment.

[elprans]

Interesting. Can you show the source for your read() function?

[immohsin]

@elprans Here is the read function.

async def read(id: str, env) 
        query = '''SELECT app_value FROM table_name WHERE id=$1;'''.
        connection = await asyncpg.connect(**creds)
        try:
            app = await connection.fetchval(query, id))
        finally:
            await connection.close()
        if not app and env is 'stage':
            app = await self.read(id, 'prod')
       return app

[immohsin]

@elprans any idea why its occurring during closing the connection object?

[elprans]

It looks like a race. The protocol handler is receiving data from the server while not expecting anything. Is finally called normally or is there a preceding exception?

[immohsin]

finally is getting called normally there is no exception.
The way I have handled now is to catch for InternalClientError exception while closing the connection.

[nikicat]

A similar error happens in my case, but a connection is closed by a CancelledError exception inside a context manager and I got
InternalClientError: got result for unknown protocol state 3

[bshakur8]

I'm also getting InternalClientError: got result for unknown protocol state 3:

asyncpg version: 0.29.0
PostgreSQL version: 9.5.10
Do you use a PostgreSQL SaaS? If so, which? GCP PostgreSQL
Python version: 3.11.9
Platform: linux
Do you use pgbouncer?: Yes
Did you install asyncpg with pip?: Yes

Got this error after a long time of running app:

	File "/usr/local/lib/python3.11/site-packages/databases/core.py", line 152, in fetch_one
 return await connection.fetch_one(query, values)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	File "/usr/local/lib/python3.11/site-packages/databases/core.py", line 269, in fetch_one
 return await self._connection.fetch_one(built_query)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	File "/usr/local/lib/python3.11/site-packages/databases/backends/postgres.py", line 189, in fetch_one
 row = await self._connection.fetchrow(query_str, *args)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	File "/usr/local/lib/python3.11/site-packages/asyncpg/connection.py", line 749, in fetchrow
 data = await self._execute(
 ^^^^^^^^^^^^^^^^^^^^
	File "/usr/local/lib/python3.11/site-packages/asyncpg/connection.py", line 1794, in _execute
 result, _ = await self.__execute(
 ^^^^^^^^^^^^^^^^^^^^^
	File "/usr/local/lib/python3.11/site-packages/asyncpg/connection.py", line 1892, in __execute
 result, stmt = await self._do_execute(
 ^^^^^^^^^^^^^^^^^^^^^^^
	File "/usr/local/lib/python3.11/site-packages/asyncpg/connection.py", line 1925, in _do_execute
 stmt = await self._get_statement(
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
	File "/usr/local/lib/python3.11/site-packages/asyncpg/connection.py", line 433, in _get_statement
 statement = await self._protocol.prepare(
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	File "asyncpg/protocol/protocol.pyx", line 166, in prepare
	File "asyncpg/protocol/protocol.pyx", line 902, in asyncpg.protocol.protocol.BaseProtocol._dispatch_result
		asyncpg.exceptions._base.InternalClientError: got result for unknown protocol state 3