Kafka Error NOT_COORDINATOR
Error code 16 · Retriable Consumer
This is not the correct coordinator.
Common Causes
- Consumer group coordinator migrated to another broker after a broker restart or partition reassignment of __consumer_offsets
- Client cached the old coordinator address and is still sending group management requests to a broker that no longer owns the partition
- Rolling restart of brokers causing coordinator to move; clients using the old coordinator get NOT_COORDINATOR until metadata refresh
Solutions
- This is retriable: the client will call FindCoordinator again and route to the correct broker; ensure 'retry.backoff.ms' allows time for metadata refresh (100-500ms)
- Verify the client library version handles NOT_COORDINATOR with a FindCoordinator retry — older client versions may not handle this correctly; upgrade to latest
- If persistent, check __consumer_offsets partition leaders: kafka-topics.sh --describe --topic __consumer_offsets; all partitions should have a valid leader
Diagnostic Commands
# Check for leaderless __consumer_offsets partitions
kafka-topics.sh --describe --topic __consumer_offsets --bootstrap-server localhost:9092 | grep 'Leader: none'
# Look for related errors in broker logs
grep -E 'NotCoordinator|FindCoordinator|Coordinator for group' /var/log/kafka/server.log | tail -20Related APIs
This error can be returned by: AddOffsetsToTxn · AddPartitionsToTxn · EndTxn · InitProducerId · OffsetFetch · WriteTxnMarkers
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