What causes FencedMemberEpochException?

The consumer sent a heartbeat or fetch request with a stale member epoch after the group coordinator already advanced the epoch (e.g., due to a rebalance or another member joining/leaving), causing the coordinator to fence the outdated member. Network partition or GC pause caused the consumer to miss heartbeat deadlines; by the time it reconnected, the group had rebalanced and the old epoch was invalidated. Consumer client is running an older version of the new consumer group protocol (KIP-848) that doesn't properly track epoch increments from the coordinator.

How do I fix FencedMemberEpochException?

The fenced consumer must stop using its current assignment and rejoin the group to obtain a fresh member epoch; standard Kafka clients handle this by issuing a new ConsumerGroupHeartbeat sequence automatically. For groups using the consumer protocol, tune the broker-side group.consumer.session.timeout.ms and group.consumer.heartbeat.interval.ms if members are being fenced because long GC pauses or network hiccups make them look dead. Ensure all consumers in the group are on the same Kafka client version supporting the new consumer protocol (Kafka 3.7+ for KIP-848). Mixed client versions cause epoch negotiation issues.

Is FencedMemberEpochException retriable?

No — FencedMemberEpochException is not retriable. Retrying the same call will not help; the underlying cause must be fixed first.

Kafka Exception `FencedMemberEpochException`

org.apache.kafka.common.errors.FencedMemberEpochException

Non-retriable Consumer

FencedMemberEpochException is a Kafka exception (org.apache.kafka.common.errors.FencedMemberEpochException).

Common Causes

The consumer sent a heartbeat or fetch request with a stale member epoch after the group coordinator already advanced the epoch (e.g., due to a rebalance or another member joining/leaving), causing the coordinator to fence the outdated member.
Network partition or GC pause caused the consumer to miss heartbeat deadlines; by the time it reconnected, the group had rebalanced and the old epoch was invalidated.
Consumer client is running an older version of the new consumer group protocol (KIP-848) that doesn't properly track epoch increments from the coordinator.

Solutions

The fenced consumer must stop using its current assignment and rejoin the group to obtain a fresh member epoch; standard Kafka clients handle this by issuing a new ConsumerGroupHeartbeat sequence automatically.
For groups using the consumer protocol, tune the broker-side group.consumer.session.timeout.ms and group.consumer.heartbeat.interval.ms if members are being fenced because long GC pauses or network hiccups make them look dead.
Ensure all consumers in the group are on the same Kafka client version supporting the new consumer protocol (Kafka 3.7+ for KIP-848). Mixed client versions cause epoch negotiation issues.

Example Stack Trace

org.apache.kafka.common.errors.FencedMemberEpochException: The member epoch is fenced by the group coordinator. The member must abandon all its partitions and rejoin.

Diagnostic Commands

# Describe consumer group offsets and lag
kafka-consumer-groups.sh --bootstrap-server localhost:9092 --describe --group <group-id>

# Look for heartbeat/session events in logs
grep 'FENCED_MEMBER_EPOCH\|fenced\|ConsumerGroupHeartbeat' /var/log/kafka/server.log | tail -50

Protocol error: FENCED_MEMBER_EPOCH (code 110)

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Kafka Exception FencedMemberEpochException

Common Causes

Solutions

Example Stack Trace

Diagnostic Commands

Related

Kafka Exception `FencedMemberEpochException`