dajac opened a new pull request, #12909: URL: https://github.com/apache/kafka/pull/12909
When a consumer group on a version prior to 2.3 is rolled upgraded to a newer version and static membership is enabled in the meantime, the consumer group remains stuck, iff the leader is still on the old version. The issue is that setting `GroupInstanceId` in the response to the leader is only supported from JoinGroup version >= 5 and that `GroupInstanceId` is not ignorable nor handled anywhere else. Hence is there is at least one static member in the group, sending the JoinGroup response to the leader fails with a serialization error. ``` org.apache.kafka.common.errors.UnsupportedVersionException: Attempted to write a non-default groupInstanceId at version 2 ``` When this happens, the member stays around until the group coordinator is bounced because a member with a non-null `awaitingJoinCallback` is never expired. ### Committer Checklist (excluded from commit message) - [ ] Verify design and implementation - [ ] Verify test coverage and CI build status - [ ] Verify documentation (including upgrade notes) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
