redis/redis-py · error · TypeError

Unsupported client type: {type(database.client)}

Error message

Unsupported client type: {type(database.client)}

What it means

Raised by `AbstractHealthCheckPolicy.get_client()` (redis/asyncio/multidb/healthcheck.py:213) when `database.client` is not one of the supported types (`AsyncRedis`, `SyncRedis`, `AsyncRedisCluster`, `SyncRedisCluster`). The health-check client builder only knows how to mirror connection kwargs for those four types; anything else (a custom wrapper, a mock, a Sentinel client) is rejected with TypeError.

Source

Thrown at redis/asyncio/multidb/healthcheck.py:213

                        nodes_manager,
                        "require_full_coverage",
                        getattr(nodes_manager, "_require_full_coverage", True),
                    )
                    client = AsyncRedisCluster(
                        host=first_node.host,
                        port=first_node.port,
                        dynamic_startup_nodes=nodes_manager._dynamic_startup_nodes,
                        address_remap=nodes_manager.address_remap,
                        require_full_coverage=require_full_coverage,
                        retry=database.client.retry,
                        **filtered_kwargs,
                    )
                else:
                    raise ValueError(
                        "Cluster client has no nodes - cannot create health check client"
                    )
            else:
                raise TypeError(f"Unsupported client type: {type(database.client)}")
            self._clients[db_id] = client

        return client

    async def close(self) -> None:
        """Close all health check clients."""
        close_tasks = [
            asyncio.create_task(client.aclose()) for client in self._clients.values()
        ]

        if close_tasks:
            await asyncio.gather(*close_tasks, return_exceptions=True)

        self._clients.clear()

    @abstractmethod
    async def _execute(self, health_check: HealthCheck, database) -> bool:
        """

View on GitHub (pinned to da03cdc7e8)

Solutions

1. Use one of the supported types directly — set `MultiDbConfig.client_class` to `Redis` or `RedisCluster` (sync or async variants as appropriate).
2. If subclassing, ensure your subclass still passes `isinstance(client, (AsyncRedis, SyncRedis, AsyncRedisCluster, SyncRedisCluster))`.
3. In tests, provide a real (or testcontainer-backed) Redis client rather than an unrelated mock as the database client.

Example fix

# before
class MyRedis(redis.asyncio.Redis):
    ...  # but constructed in a way isinstance fails, or a non-Redis wrapper
client = MultiDBClient(MultiDbConfig(
    databases_config=[DatabaseConfig(client_kwargs={})],
    client_class=MyRedis,  # if MyRedis is not a Redis subclass
))

# after
client = MultiDBClient(MultiDbConfig(
    databases_config=[DatabaseConfig(from_url='redis://host:6379/0')],
    client_class=redis.asyncio.Redis,
))

import redis.asyncio as aioredis
from redis.asyncio import RedisCluster as AsyncRedisCluster
from redis.client import Redis as SyncRedis
from redis.cluster import RedisCluster as SyncRedisCluster

def client_is_supported(database) -> bool:
    return isinstance(database.client, (aioredis.Redis, SyncRedis, AsyncRedisCluster, SyncRedisCluster))

import redis.asyncio as aioredis
from redis.asyncio import RedisCluster as AsyncRedisCluster
from redis.client import Redis as SyncRedis
from redis.cluster import RedisCluster as SyncRedisCluster

def is_supported_client(database) -> bool:
    return isinstance(database.client, (aioredis.Redis, SyncRedis, AsyncRedisCluster, SyncRedisCluster))

try:
    await client.initialize()
except TypeError as e:
    if 'Unsupported client type' in str(e):
        # switch client_class to Redis/RedisCluster in MultiDbConfig
        ...
    raise

When it happens

Trigger: Passing a `DatabaseConfig` whose underlying client is a custom subclass or a non-Redis object (e.g. a test double/mock, a wrapped client, or a Sentinel-managed client) and triggering `get_client()` during a health check.

Common situations: Subclassing `redis.asyncio.Redis` in a way that breaks `isinstance`; injecting a mock client in tests; using a third-party Redis wrapper as the `client_class` in MultiDbConfig.

Related errors

• Initial health check failed. Initial health check policy: {s
• Cluster client has no nodes - cannot create health check cli
• Initial connection failed - no active database found
• Given database is not a member of database list
• Cannot set active database, database is unhealthy

AI-assisted analysis of redis/redis-py@da03cdc7e8 (2026-08-04). Data as JSON: /data/errors/01635852b4a53022.json. Report an issue: GitHub.