redis/redis-py · critical · RedisClusterException

Cluster mode is not enabled on this node

Error message

Cluster mode is not enabled on this node

What it means

Raised as a RedisClusterException during initial topology discovery when executing CLUSTER SLOTS on a startup node raises a ResponseError. A ResponseError to CLUSTER SLOTS means the node is not running in cluster mode (it is a standalone Redis instance). The catch at cluster.py:2699-2702 converts this into a clear error. This is raised per-node and only surfaces if no other startup node succeeds.

Solutions

1. Use redis.Redis (standalone client) instead of RedisCluster if the server is not in cluster mode.
2. Enable cluster mode in redis.conf by setting 'cluster-enabled yes' and restart the Redis server.
3. Verify with redis-cli -h host -p port CLUSTER INFO that the node reports cluster_enabled:1.

Example fix

// before
client = RedisCluster(host='localhost', port=6379)  # standalone Redis

// after (standalone server)
from redis import Redis
client = Redis(host='localhost', port=6379)

import redis
# Verify cluster mode is enabled before using RedisCluster
standalone = redis.Redis(host, port)
try:
    info = standalone.cluster('INFO')
    assert 'cluster_enabled:1' in info
except redis.ResponseError:
    raise RuntimeError('This server is not in cluster mode; use redis.Redis instead')

def is_cluster_node(host: str, port: int) -> bool:
    import redis
    try:
        info = redis.Redis(host, port).cluster('INFO')
        return 'cluster_enabled:1' in info
    except redis.ResponseError:
        return False

from redis.exceptions import RedisClusterException
try:
    client = RedisCluster(host, port)
except RedisClusterException as e:
    if 'Cluster mode is not enabled' in str(e):
        from redis import Redis
        client = Redis(host, port)  # fall back to standalone

When it happens

Trigger: Constructing RedisCluster(host, port) where host:port points to a standalone (non-cluster) Redis server. The client tries CLUSTER SLOTS, gets a ResponseError (ERR This instance has cluster support disabled), and wraps it.

Common situations: Developer uses RedisCluster against a single standalone Redis instance, or the cluster-mode-enabled setting (cluster-enabled yes) was not set in redis.conf, or connecting through a proxy that strips cluster commands.

Related errors

• Cluster mode is not enabled on this node
• All slots are not covered after query all startup_nodes.
• Argument 'db' must be 0 or None in cluster mode
• Cache must implement CacheInterface
• Cannot disable maintenance notifications after enabling them

AI-assisted analysis of redis/redis-py@6a6b581b48 (2026-08-10). Data as JSON: /api/errors/baa2eb0ce98f934a. Report an issue: GitHub.

Appendix: source

Thrown at redis/cluster.py:2700

                            **kwargs,
                        )
                        if startup_node in self.startup_nodes.values():
                            self.startup_nodes[startup_node.name].redis_connection = r
                        else:
                            startup_node.redis_connection = r
                    try:
                        # Make sure cluster mode is enabled on this node
                        cluster_slots = str_if_bytes(r.execute_command("CLUSTER SLOTS"))
                        if disconnect_startup_nodes_pools:
                            with r.connection_pool._lock:
                                # take care to clear connections before we move on
                                # mark all active connections for reconnect - they will be
                                # reconnected on next use, but will allow current in flight commands to complete first
                                r.connection_pool.update_active_connections_for_reconnect()
                                # Needed to clear READONLY state when it is no longer applicable
                                r.connection_pool.disconnect_free_connections()
                    except ResponseError:
                        raise RedisClusterException(
                            "Cluster mode is not enabled on this node"
                        )
                    startup_nodes_reachable = True
                except Exception as e:
                    # Try the next startup node.
                    # The exception is saved and raised only if we have no more nodes.
                    exception = e
                    continue

                # CLUSTER SLOTS command results in the following output:
                # [[slot_section[from_slot,to_slot,master,replica1,...,replicaN]]]
                # where each node contains the following list: [IP, port, node_id]
                # Therefore, cluster_slots[0][2][0] will be the IP address of the
                # primary node of the first slot section.
                # If there's only one server in the cluster, its ``host`` is ''
                # Fix it to the host in startup_nodes
                if (
                    len(cluster_slots) == 1

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