redis/redis-py · error · RedisError

Hiredis is not installed

Error message

Hiredis is not installed

What it means

Raised by _HiredisParser.__init__() when redis.utils.HIREDIS_AVAILABLE is False - i.e. the optional hiredis-py package is not importable. The parser is only constructed when the connection is configured to use the hiredis parser; without the C extension the parser cannot be created. Plain RedisError, error_type=SERVER.

Source

Thrown at redis/_parsers/hiredis.py:112

        return bool(revents & closed_flags)
    except OSError:
        # The socket is errored (POLLERR/POLLNVAL); nothing left to read.
        return True


class _HiredisReaderArgs(TypedDict, total=False):
    protocolError: Callable[[str], Exception]
    replyError: Callable[[str], Exception]
    encoding: Optional[str]
    errors: Optional[str]


class _HiredisParser(BaseParser, PushNotificationsParser):
    "Parser class for connections using Hiredis"

    def __init__(self, socket_read_size):
        if not HIREDIS_AVAILABLE:
            raise RedisError("Hiredis is not installed")
        self.socket_read_size = socket_read_size
        self._buffer = bytearray(socket_read_size)
        self.pubsub_push_handler_func = self.handle_pubsub_push_response
        self.node_moving_push_handler_func = None
        self.maintenance_push_handler_func = None
        self.oss_cluster_maint_push_handler_func = None
        self.invalidation_push_handler_func = None
        self._hiredis_PushNotificationType = None

    def __del__(self):
        try:
            self.on_disconnect()
        except Exception:
            pass

    def handle_pubsub_push_response(self, response):
        logger = getLogger("push_response")
        logger.debug("Push response: %s", response)

View on GitHub (pinned to da03cdc7e8)

Solutions

1. Install hiredis: pip install hiredis (or pip install redis[hiredis]).
2. Verify the install imports: python -c 'import hiredis; print(hiredis.__version__)'.
3. If you cannot install hiredis, drop the parser_class override so the pure-Python parser is used.
4. Rebuild hiredis against the running Python ABI after a Python version bump.

Example fix

// before
r = redis.Redis(..., parser_class=redis.parsers.HiredisParser)
# RedisError: Hiredis is not installed

// after
# option A: install it
#   pip install hiredis
# option B: fall back to the pure-Python parser
r = redis.Redis(...)  # do not set parser_class

# Verify hiredis is importable before constructing a client that needs it
import importlib.util, redis.utils
if not importlib.util.find_spec("hiredis"):
    raise RuntimeError("install 'hiredis' or drop the parser_class override")
assert redis.utils.HIREDIS_AVAILABLE

try:
    r = redis.Redis(..., parser_class=redis.parsers.HiredisParser)
except redis.exceptions.RedisError as e:
    if "Hiredis is not installed" in str(e):
        # fall back to the pure-Python parser
        r = redis.Redis(...)

When it happens

Trigger: Setting parser_class=_HiredisParser (or via a client config that selects it) in an environment where hiredis is not installed; the installed hiredis is older than 3.2.0 (HIREDIS_AVAILABLE checks importability/version); broken hiredis build that fails to import.

Common situations: Deploying without the 'hiredis' extra (pip install redis[hiredis]); using a slim Docker image lacking build tools; mixed Python versions in a venv where hiredis was compiled for a different ABI; pinning redis-py but forgetting the optional C extension.

Related errors

• Connection closed by server.
• Maintenance notifications are only supported with hiredis an
• {cmd_name.upper()} command doesn't exist in Redis commands
• Subcommand {subcommand_name} not found in command {command_n
• Command {command_name} not found in commands

AI-assisted analysis of redis/redis-py@da03cdc7e8 (2026-08-04). Data as JSON: /data/errors/5067ab8df9750e27.json. Report an issue: GitHub.