{"record":{"id":"ce0bf8684592e3e5","repo":"redis/redis-py","slug":"cluster-node-target-node-name-has-no-redis-conne","errorCode":null,"errorMessage":"Cluster Node {target_node.name} has no redis_connection","messagePattern":"Cluster Node (.+?) has no redis_connection","errorType":"exception","errorClass":"RedisClusterException","httpStatus":null,"severity":"error","filePath":"redis/cluster.py","lineNumber":1185,"sourceCode":"        self.nodes_manager.default_node = node\n        return True\n\n    def set_retry(self, retry: Retry) -> None:\n        self.retry = retry\n\n    def monitor(self, target_node=None):\n        \"\"\"\n        Returns a Monitor object for the specified target node.\n        The default cluster node will be selected if no target node was\n        specified.\n        Monitor is useful for handling the MONITOR command to the redis server.\n        next_command() method returns one command from monitor\n        listen() method yields commands from monitor.\n        \"\"\"\n        if target_node is None:\n            target_node = self.get_default_node()\n        if target_node.redis_connection is None:\n            raise RedisClusterException(\n                f\"Cluster Node {target_node.name} has no redis_connection\"\n            )\n        return target_node.redis_connection.monitor()\n\n    def pubsub(self, node=None, host=None, port=None, **kwargs):\n        \"\"\"\n        Allows passing a ClusterNode, or host&port, to get a pubsub instance\n        connected to the specified node\n        \"\"\"\n        return ClusterPubSub(self, node=node, host=host, port=port, **kwargs)\n\n    def keyspace_notifications(\n        self,\n        key_prefix: Union[str, bytes, None] = None,\n        ignore_subscribe_messages: bool = True,\n    ) -> \"ClusterKeyspaceNotifications\":\n        \"\"\"\n        Return a :class:`~redis.keyspace_notifications.ClusterKeyspaceNotifications`","sourceCodeStart":1167,"sourceCodeEnd":1203,"githubUrl":"https://github.com/redis/redis-py/blob/6a6b581b48225afa0b76912d1028c6035baee932/redis/cluster.py#L1167-L1203","documentation":"Raised as a RedisClusterException by the monitor() method when the target ClusterNode's redis_connection attribute is None, meaning no live Redis connection object has been created for that node. The monitor() method needs a raw connection to stream MONITOR output, so a missing connection is a hard failure.","triggerScenarios":"Calling client.monitor(target_node=some_node) where some_node is a ClusterNode whose redis_connection was never initialized (e.g., a node discovered during topology mapping but never connected to). The check is at cluster.py:1184-1187.","commonSituations":"Passing a node obtained from get_nodes() or a slot-cache lookup whose lazy connection was never opened, or a node that has been removed from the cluster but still referenced by the application.","solutions":["Call client.get_redis_connection(target_node) first to force lazy connection creation before calling monitor().","If no target_node is passed, let the client pick the default node (pass target_node=None).","Verify the node is still part of the cluster topology with client.get_node(host, port) before using it."],"exampleFix":"// before\nm = client.monitor(target_node=some_node)\n\n// after\nclient.get_redis_connection(some_node)\nm = client.monitor(target_node=some_node)","handlingStrategy":"validation","validationCode":"# Force connection before calling monitor()\nif target_node and target_node.redis_connection is None:\n    client.get_redis_connection(target_node)","typeGuard":"def node_has_connection(node) -> bool:\n    return node.redis_connection is not None","tryCatchPattern":"from redis.exceptions import RedisClusterException\ntry:\n    m = client.monitor(target_node=node)\nexcept RedisClusterException as e:\n    if 'has no redis_connection' in str(e):\n        client.get_redis_connection(node)\n        m = client.monitor(target_node=node)","preventionTips":["Call client.get_redis_connection(node) to lazily open a connection before monitor().","Let the client pick the default node by omitting target_node.","Verify the node is still in the cluster before using it."],"tags":["monitor","connection","cluster"],"backgroundTag":null,"analyzedSha":"6a6b581b48225afa0b76912d1028c6035baee932","analyzedAt":"2026-08-10T12:52:44.840Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-21T04:17:39.646Z"}