There has been plenty of changes in the GroupCoordinator and co between these two releases: https://github.com/apache/kafka/commit/40b1dd3f495a59abef8a0cba5450526994c92c04#diff-96e4cf31cd54def6b2fb3f7a118c1db3
It might be related to this: https://github.com/apache/kafka/commit/4b003d8bcfffded55a00b8ecc9eed8eb373fb6c7#diff-d2461f78377b588c4f7e2fe8223d5679R633 If your group is empty, your group is marked dead, when the group is dead, no matter what you do, it’ll reply with: https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/coordinator/GroupCoordinator.scala#L353 Food for thought. – Best regards, Radek Gruchalski ra...@gruchalski.com On November 28, 2016 at 9:04:16 PM, Bart Vercammen (b...@cloutrix.com) wrote: Hi, It seems that consumer group rebalance is broken in Kafka 0.10.1.0 ? When running a small test-project : - consumers running in own JVM (with different 'client.id') - producer running in own JVM - kafka broker : the embedded kafka : KafkaServerStartable It looks like the consumers loose their hart-beat after a rebalance got triggered. In the logs on the consumer I can actually see that the heartbeat failed due to "invalid member_id" When running the exact same code on a 0.10.0.1 setup, all works perfectly. Anyone else seen this problem? Greets, Bart