How to fix CLUSTERDOWN The cluster is down in Redis

What this error means

The "CLUSTERDOWN The cluster is down" error indicates that the Redis cluster has entered an unavailable state. By default, Redis cluster nodes are configured to refuse all queries if they detect that at least one hash slot (a portion of the data space) is not covered by any working node. Redis cluster divides the keyspace into 16,384 hash slots. Each key maps to exactly one slot, and each cluster node is responsible for a range of slots. When master nodes and all their replicas go down simultaneously, the slots they manage become uncovered, triggering a cluster-wide shutdown. This behavior is controlled by the `cluster-require-full-coverage` configuration setting (default: yes). It exists as a safety mechanism to prevent the cluster from serving stale or incorrect data during partial outages. **Common scenarios:** - A master node and all its replicas crash simultaneously - Network partitions isolating master nodes from the cluster - Long-running commands or Lua scripts cause nodes to appear dead to the cluster - Slot migration operations hang, leaving slots in an inconsistent state - Multiple nodes fail before the cluster can rebalance

Typical symptoms

• Redis clients receive 'CLUSTERDOWN The cluster is down' error
• All Redis commands fail with cluster unavailable message
• redis-cli cluster info shows missing slots
• Application logs show connection failures to Redis cluster
• Cluster reports unhealthy or partially down state
• Some nodes are reachable but cluster refuses reads/writes

Common causes

1. One or more master nodes and all their replicas are offline
2. Network partition isolating masters from the rest of the cluster
3. Long-running Redis commands block heartbeat ping/pong messages
4. Lua scripts executing for too long (lua-time-limit exceeded)
5. Hash slot migration is stuck or incomplete
6. Cluster node timeout triggered, marking healthy nodes as failed
7. Insufficient memory or disk space causing nodes to crash
8. Incompatible Redis versions in cluster nodes

How to fix "CLUSTERDOWN The cluster is down"

# On any accessible cluster node
redis-cli -h <node-ip> -p <port> cluster info

# Check detailed slot status
redis-cli -h <node-ip> -p <port> cluster slots

# Check individual node status
redis-cli -h <node-ip> -p <port> cluster nodes

# From a node that's still accessible
redis-cli -h <node-ip> -p <port> cluster nodes | grep -E 'master|slave'

# Output shows node status (connected/disconnected)
# Example:
# 1a2b3c... 10.0.0.1:6379 master - 0 1500000000000 1 connected 0-5460
# 4d5e6f... 10.0.0.2:6379 slave 1a2b3c... 0 1500000001000 1 connected

# Via systemd (Linux)
sudo systemctl restart redis-server

# Or if using redis_6379 naming convention
sudo systemctl restart redis_6379

# Via direct command
redis-server /etc/redis/redis.conf

# Check if the node rejoins the cluster
redis-cli -h <node-ip> -p <port> cluster info

# Watch cluster recovery
watch -n 1 'redis-cli -h <node-ip> -p <port> cluster info | grep cluster_state'

# Find stuck slots (showing importing/migrating state)
redis-cli -h <node-ip> -p <port> cluster slots

# On BOTH the source and target nodes, stabilize the slot
redis-cli -h <source-node> -p <port> CLUSTER SETSLOT <slot-number> STABLE
redis-cli -h <target-node> -p <port> CLUSTER SETSLOT <slot-number> STABLE

# Example: Stabilize slot 5000
redis-cli -h 10.0.0.1 -p 6379 CLUSTER SETSLOT 5000 STABLE
redis-cli -h 10.0.0.2 -p 6379 CLUSTER SETSLOT 5000 STABLE

# Verify the cluster recovers
redis-cli -h <node-ip> -p <port> cluster info

# On any accessible node
redis-cli -h <node-ip> -p <port> CONFIG SET cluster-require-full-coverage no

# Verify the change
redis-cli -h <node-ip> -p <port> CONFIG GET cluster-require-full-coverage

# The cluster should now serve requests for available slots
redis-cli -h <node-ip> -p <port> cluster info

# Use redis-cli --cluster fix command (Redis 5.0+)
redis-cli --cluster fix <node-ip>:<port>

# For older Redis versions, use redis-trib.rb
./redis-trib.rb fix <node-ip>:<port>

# Check the results
redis-cli -h <node-ip> -p <port> cluster info

# On any cluster node, temporarily adjust timeouts
redis-cli -h <node-ip> -p <port> CONFIG SET cluster-node-timeout 15000

# Also check and adjust Lua script timeout (default 5000ms)
redis-cli -h <node-ip> -p <port> CONFIG SET lua-time-limit 10000

# Verify changes
redis-cli -h <node-ip> -p <port> CONFIG GET cluster-node-timeout
redis-cli -h <node-ip> -p <port> CONFIG GET lua-time-limit

# Real-time cluster status monitoring
while true; do
  echo "=== Cluster Status at $(date) ==="
  redis-cli -h <node-ip> -p <port> cluster info | grep cluster_state
  redis-cli -h <node-ip> -p <port> cluster info | grep cluster_slots
  redis-cli -h <node-ip> -p <port> cluster nodes | grep -E 'master|slave' | awk '{print $1, $2, $3, $4}'
  sleep 10
done

# Or use redis-cli's built-in monitor
redis-cli -h <node-ip> -p <port> --cluster check <node-ip>:<port>

# Check Redis logs for errors
tail -f /var/log/redis/redis-server.log

# Monitor system resources on affected nodes
watch -n 1 'free -h && df -h && ps aux | grep redis'

# Check for out-of-memory conditions
redis-cli -h <node-ip> -p <port> info memory

# Look for replication lag (if applicable)
redis-cli -h <node-ip> -p <port> info replication

Advanced notes

Frequently asked questions

What does "CLUSTERDOWN The cluster is down" mean?

The "CLUSTERDOWN The cluster is down" error indicates that the Redis cluster has entered an unavailable state. By default, Redis cluster nodes are configured to refuse all queries if they detect that at least one hash slot (a portion of the data space) is not covered by any working node. Redis cluster divides the keyspace into 16,384 hash slots.

How do I fix "CLUSTERDOWN The cluster is down"?

This error occurs when a Redis cluster becomes unavailable due to node failures or missing hash slot coverage. The cluster stops accepting requests until all hash slots are covered again by available nodes.

What causes "CLUSTERDOWN The cluster is down"?

One or more master nodes and all their replicas are offline Network partition isolating masters from the rest of the cluster Long-running Redis commands block heartbeat ping/pong messages

Is the "CLUSTERDOWN The cluster is down" error serious?

Yes. This is a high-severity error that usually blocks work until it is fixed, but the steps above resolve it.

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Official resources & further reading

• 📚Redis Official Documentation
• 📖
  Redis Cluster Documentation(Official Docs)
• 📖
  Redis Sentinel Documentation(Official Docs)
• 🐙
  Redis Cluster - Getting Cluster Down Errors(GitHub)
• 🐙
  Getting JedisClusterException CLUSTERDOWN(GitHub)
• 💬
  CLUSTERDOWN but the cluster isn't down - Redis Discussion(Stack Overflow)
• 💬
  Single master failure causing CLUSTERDOWN - Redis Discussion(Stack Overflow)
• Redis CLUSTERDOWN Diagnosis Guide
• How we tamed the Redis Cluster Down demon - Games24x7
• Mitigating Failures - AWS ElastiCache
• Redis Cluster Persistence - Google Cloud