dajac commented on code in PR #18046: URL: https://github.com/apache/kafka/pull/18046#discussion_r1871414994
########## group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java: ########## @@ -1053,6 +1055,12 @@ ConsumerGroup convertToConsumerGroup(ClassicGroup classicGroup, List<Coordinator throw new GroupIdNotFoundException("Cannot upgrade the classic group " + classicGroup.groupId() + " to consumer group because the embedded consumer protocol is malformed."); + } catch (UnsupportedVersionException e) { + log.warn("Cannot upgrade the classic group " + classicGroup.groupId() + + " to consumer group: " + e.getMessage() + ".", e); + + throw new GroupIdNotFoundException("Cannot upgrade the classic group " + classicGroup.groupId() + + " to consumer group because a custom assignor is in use."); Review Comment: > I had a look and there are three reasons in [validateOnlineUpgrade](https://github.com/apache/kafka/blob/e99561e1f30a30f9b151669a78d340f286a3ead6/group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java#L1008-L1023) that we convert to "Group %s is not a consumer group": I wonder whether we should extend the error message that we provide to the user. "not a consumer group" does not say much. What do you think? -- 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