# org.apache.kafka.common.errors.StaleMemberEpochException: The member epoch 5 has been fenced by the group coordinator

- **ID:** `kafka/consumer-group-stale-metadata`
- **Domain:** kafka
- **Category:** runtime_error
- **Verification:** ai_generated
- **Fix Rate:** 82%

## Root Cause

Consumer member's epoch (generation) is outdated because the group coordinator has rebalanced or the consumer's session timed out, leading to a fenced member.

## Workarounds

1. **Implement a consumer rebalance listener to detect rebalances and reset state. For Java consumers: `consumer.subscribe(Collections.singletonList(topic), new ConsumerRebalanceListener() { ... })`** (85% success)
   ```
   Implement a consumer rebalance listener to detect rebalances and reset state. For Java consumers: `consumer.subscribe(Collections.singletonList(topic), new ConsumerRebalanceListener() { ... })`
   ```
2. **Increase 'heartbeat.interval.ms' to a value lower than 'session.timeout.ms' (e.g., set heartbeat to 1000 ms and session timeout to 10000 ms) to ensure timely heartbeats and reduce session expiry.** (80% success)
   ```
   Increase 'heartbeat.interval.ms' to a value lower than 'session.timeout.ms' (e.g., set heartbeat to 1000 ms and session timeout to 10000 ms) to ensure timely heartbeats and reduce session expiry.
   ```
3. **If using static group membership, ensure 'group.instance.id' is unique per consumer and stable across restarts. Example: `props.put(ConsumerConfig.GROUP_INSTANCE_ID_CONFIG, "consumer-1");`** (75% success)
   ```
   If using static group membership, ensure 'group.instance.id' is unique per consumer and stable across restarts. Example: `props.put(ConsumerConfig.GROUP_INSTANCE_ID_CONFIG, "consumer-1");`
   ```

## Dead Ends

- **** — This can make the consumer unresponsive for longer periods, worsening rebalance issues and causing the group to stall; it does not prevent epoch fencing due to rebalances. (50% fail)
- **** — Static membership only prevents unnecessary rebalances during brief disconnections; if the consumer actually fails or is fenced, the epoch will still be stale. (40% fail)
- **** — This causes a full rebalance and may temporarily resolve the error, but the underlying cause (e.g., network issues, slow processing) remains, so the error will recur. (70% fail)