redis/redis-py · error · ResponseError

Wrong number of response items from pipeline execution

Error message

Wrong number of response items from pipeline execution

What it means

Raised by Pipeline._execute_transaction (redis/asyncio/client.py:2082) when the number of items in the EXEC response does not equal the number of queued commands. This indicates a protocol desync — the client and server disagree about how many replies are on the wire. The library disconnects the connection (to reset protocol state) and raises ResponseError.

Source

Thrown at redis/asyncio/client.py:2082

        except ExecAbortError as err:
            if errors:
                raise errors[0][1] from err
            raise

        # EXEC clears any watched keys
        self.watching = False

        if response is None:
            raise WatchError("Watched variable changed.") from None

        # put any parse errors into the response
        for i, e in errors:
            response.insert(i, e)

        if len(response) != len(commands):
            if self.connection:
                await self.connection.disconnect()
            raise ResponseError(
                "Wrong number of response items from pipeline execution"
            ) from None

        # find any errors in the response and raise if necessary
        if raise_on_error:
            self.raise_first_error(commands, response)

        # We have to run response callbacks manually
        data = []
        for r, cmd in zip(response, commands):
            if not isinstance(r, Exception):
                args, options = cmd
                command_name = args[0]

                # Remove keys entry, it needs only for cache.
                options.pop("keys", None)

                if command_name in self.response_callbacks:

View on GitHub (pinned to da03cdc7e8)

Solutions

1. Report it as a bug: capture redis-py version, server version, and the exact command stack.
2. Ensure no custom response_callback consumes/returns multiple frames for a single command.
3. Disconnect and rebuild the client (the library already disconnects the offending connection).
4. Test against a direct Redis node rather than a proxy/gateway to isolate the cause.

from redis.exceptions import ResponseError
try:
    await pipe.execute()
except ResponseError as e:
    if 'Wrong number of response items' in str(e):
        log.exception('pipeline protocol desync; reconnecting')
        await r.connection_pool.disconnect()
    raise

When it happens

Trigger: A corrupted or out-of-sync connection where EXEC returns the wrong arity: typically a library/server bug, a partial command drop, or commands that the server rejected in a way that changed reply count. This is a defensive check, not normal control flow.

Common situations: Extremely rare in normal use; seen with intermediary proxies that mis-shape transaction replies, custom response callbacks that consume extra frames, or version skew between client and server on a command's reply shape.

Related errors

• Cannot issue nested calls to MULTI
• Commands without an initial WATCH have already been issued
• A {type(error).__name__} occurred while watching one or more
• Watched variable changed.
• Cannot issue a WATCH after a MULTI

AI-assisted analysis of redis/redis-py@da03cdc7e8 (2026-08-04). Data as JSON: /data/errors/13ac6c5b43fd0daf.json. Report an issue: GitHub.