Kafka Error COORDINATOR_LOAD_IN_PROGRESS
Error code 14 · Retriable Consumer
The coordinator is loading and hence can't process requests.
Common Causes
- The __consumer_offsets partition coordinator broker just became the leader and is loading committed offsets from the log into memory
- Coordinator broker restarted or the partition was reassigned, triggering a reload of potentially millions of offset records
- Large number of consumer groups with long offset histories causing slow coordinator startup under GC pressure
Solutions
- This is transient and retriable by design; ensure consumer client's 'retry.backoff.ms' and coordinator retry logic are configured to wait (default 100ms); typically resolves in seconds
- If it lasts for minutes, inspect the broker leading the affected __consumer_offsets partition for GC pauses, slow disk, or log recovery delay; the coordinator cannot serve the group until offset load finishes
- Reduce long-term coordinator load by expiring unused groups with offsets.retention.minutes, cleaning up dead groups, and keeping __consumer_offsets healthy and compacted
Diagnostic Commands
# Look for coordinator loading events in logs
grep -E 'Loading offsets|Finished loading offsets|CoordinatorLoadInProgress' /var/log/kafka/server.log | tail -20
# List all consumer groups
kafka-consumer-groups.sh --bootstrap-server localhost:9092 --list 2>&1 | head -5Related APIs
This error can be returned by: EndTxn · Heartbeat · InitProducerId · ListTransactions · TxnOffsetCommit · WriteTxnMarkers
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