# ERR CLUSTERDOWN The cluster is down - node timeout, replica not synced

- **ID:** `redis/cluster-node-timeout-replica`
- **Domain:** redis
- **Category:** network_error
- **Error Code:** `ERR`
- **Verification:** ai_generated
- **Fix Rate:** 82%

## Root Cause

A cluster node timed out and its replica is not fully synced, causing the cluster to lose quorum and mark itself as down.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 7.2.0 | active | — | — |
| 7.4.0 | active | — | — |
| 8.0.0 | active | — | — |

## Workarounds

1. **Force the replica to sync: CLUSTER REPLICATE <master-node-id>. Then wait for replication to complete using CLUSTER INFO.** (80% success)
   ```
   Force the replica to sync: CLUSTER REPLICATE <master-node-id>. Then wait for replication to complete using CLUSTER INFO.
   ```
2. **If the master is permanently down, promote the replica to master: CLUSTER FAILOVER FORCE on the replica node.** (85% success)
   ```
   If the master is permanently down, promote the replica to master: CLUSTER FAILOVER FORCE on the replica node.
   ```
3. **Increase cluster-node-timeout to a higher value (e.g., 30000ms) to tolerate transient network issues: CONFIG SET cluster-node-timeout 30000.** (70% success)
   ```
   Increase cluster-node-timeout to a higher value (e.g., 30000ms) to tolerate transient network issues: CONFIG SET cluster-node-timeout 30000.
   ```

## Dead Ends

- **** — Restarting the failed node without fixing the replica sync will cause the same timeout again because the replica is still behind. (70% fail)
- **** — Increasing cluster-node-timeout alone without addressing network issues or replica sync lag will not prevent future timeouts. (50% fail)