[jira] [Created] (KAFKA-19331) No error handling for leader unregistered in applyLocalFollowersDelta

["Luke Chen (Jira)" <ji...@apache.org>]

Luke Chen created KAFKA-19331:
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             Summary: No error handling for leader unregistered in applyLocalFollowersDelta 
                 Key: KAFKA-19331
                 URL: https://issues.apache.org/jira/browse/KAFKA-19331
             Project: Kafka
          Issue Type: Bug
            Reporter: Luke Chen


In ReplicaManager#applyLocalFollowersDelta, when we prepare for fetching from the leader, we'll check if the leader node info is in metadata image. If somehow it didn't include in the newImage, we'll log something like:

 
{code:java}
[2025-05-26 15:25:58,124] TRACE [Broker id=4] Unable to start fetching quickstart-events-0 with topic ID Some(Dn9K0BB8QWuj4PqcJD0nrA) from leader Some(2) because it is not alive. (state.change.logger)
[2025-05-26 15:25:58,124] INFO [Broker id=4] Started fetchers as part of become-follower for 1 partitions (state.change.logger)
{code}
 

It's confusing to users to see it's unable to fetch, then start fetch. And in the end, it's not actually fetching... We should handling the error well by updating the `FailedPartition` and not updating other successful result status.

 



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