What causes "Node {host}:{port} doesn't exist in the cluster" in redis/redis-py?

Verify the node exists: client.get_node(host, port) returns a ClusterNode before passing it to pubsub().

redis/redis-py · error · RedisClusterException

Node : doesn't exist in the cluster

Error message

Node {host}:{port} doesn't exist in the cluster

What it means

Raised as a RedisClusterException by _raise_on_invalid_node() (used by ClusterPubSub) when the provided node is None or is not found in the cluster's node cache (cluster.py:3036-3039). This means the host:port or ClusterNode passed to pubsub() does not correspond to any known node in the current topology.

Solutions

Verify the node exists: client.get_node(host, port) returns a ClusterNode before passing it to pubsub().
Use a known node from client.get_nodes() or client.get_primaries() instead of a hardcoded address.
If using a ClusterNode object, ensure it came from the same client instance's topology.

Example fix

// before
ps = client.pubsub(host='10.0.0.99', port=7000)  # wrong address

// after
nodes = client.get_primaries()
ps = client.pubsub(node=nodes[0])

Defensive patterns

Strategy: validation

Validate before calling

# Verify the node exists in the cluster before using it
node = client.get_node(host, port)
if node is None:
    raise ValueError(f'Node {host}:{port} is not in the cluster')
ps = client.pubsub(node=node)

Type guard

def node_exists_in_cluster(client, host, port) -> bool:
    return client.get_node(host=host, port=port) is not None

Try / catch

from redis.exceptions import RedisClusterException
try:
    ps = client.pubsub(host=h, port=p)
except RedisClusterException as e:
    if "doesn't exist in the cluster" in str(e):
        ps = client.pubsub(node=client.get_primaries()[0])

Prevention

Use client.get_node(host, port) to confirm a node exists before passing it to pubsub().
Prefer passing ClusterNode objects from client.get_primaries()/get_nodes() over hardcoded addresses.
Refresh topology before using stale addresses after cluster changes.

When it happens

Trigger: Calling client.pubsub(host=h, port=p) or client.pubsub(node=n) where h:p or n is not a member of the cluster (wrong address, typo, or a node that was removed). get_node() returns None or get_node(node_name=...) returns None.

Common situations: Using a stale host:port from before a cluster topology change, typo in address, or passing a ClusterNode from a different cluster instance.

Related errors

AI-assisted analysis of redis/redis-py@6a6b581b48 (2026-08-10). Data as JSON: /api/errors/da20cf7c0094bda5. Report an issue: GitHub.

Appendix: source

Thrown at redis/cluster.py:3037

        else:
            # nothing passed by the user. set node to None
            pubsub_node = None

        self.node = pubsub_node

    def get_pubsub_node(self):
        """
        Get the node that is being used as the pubsub connection
        """
        return self.node

    def _raise_on_invalid_node(self, redis_cluster, node, host, port):
        """
        Raise a RedisClusterException if the node is None or doesn't exist in
        the cluster.
        """
        if node is None or redis_cluster.get_node(node_name=node.name) is None:
            raise RedisClusterException(
                f"Node {host}:{port} doesn't exist in the cluster"
            )

    def execute_command(self, *args):
        """
        Execute a subscribe/unsubscribe command.

        Taken code from redis-py and tweak to make it work within a cluster.
        """
        # NOTE: don't parse the response in this function -- it could pull a
        # legitimate message off the stack if the connection is already
        # subscribed to one or more channels

        if self.connection is None:
            if self.connection_pool is None:
                if len(args) > 1:
                    # Hash the first channel and get one of the nodes holding
                    # this slot

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