Sample stacktraces which cause the FetchetThread to crash while the broker keeps running:

[ReplicaFetcher replicaId=1008, leaderId=1011, fetcherId=0] org.apache.kafka.common.KafkaException: Error processing data for partition partition-a-33 offset 28442022
        at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$7(AbstractFetcherThread.scala:208)
        at scala.Option.foreach(Option.scala:257)
        at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$6(AbstractFetcherThread.scala:172)
        at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$6$adapted(AbstractFetcherThread.scala:169)
        at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:59)
        at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:52)
        at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
        at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$5(AbstractFetcherThread.scala:169)
        at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
        at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:251)
        at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:169)
        at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:114)
        at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:82)
Caused by: kafka.common.UnexpectedAppendOffsetException: Unexpected offset in append to partition-a-33. First offset 28442021 is less than the next offset 28442022. First 10 offsets in append: List(28442021, 28442022, 28442023, 28442024, 28442025, 28442026, 28442027, 28442028, 28442029, 28442030), last offset in append: 28442043. Log start offset = 27823537
        at kafka.log.Log.$anonfun$append$2(Log.scala:830)
        at kafka.log.Log.maybeHandleIOException(Log.scala:1837)
        at kafka.log.Log.append(Log.scala:752)
        at kafka.log.Log.appendAsFollower(Log.scala:733)
        at kafka.cluster.Partition.$anonfun$doAppendRecordsToFollowerOrFutureReplica$1(Partition.scala:589)
        at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:251)
        at kafka.utils.CoreUtils$.inReadLock(CoreUtils.scala:257)
        at kafka.cluster.Partition.doAppendRecordsToFollowerOrFutureReplica(Partition.scala:577)
        at kafka.cluster.Partition.appendRecordsToFollowerOrFutureReplica(Partition.scala:596)
        at kafka.server.ReplicaFetcherThread.processPartitionData(ReplicaFetcherThread.scala:129)
        at kafka.server.ReplicaFetcherThread.processPartitionData(ReplicaFetcherThread.scala:43)
        at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$7(AbstractFetcherThread.scala:186)
        ... 12 more

[ReplicaFetcher replicaId=1011, leaderId=1014, fetcherId=0] Error due to org.apache.kafka.common.KafkaException: Error processing data for partition partition-b-97 offset 1388
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$7(AbstractFetcherThread.scala:208)
	at scala.Option.foreach(Option.scala:257)
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$6(AbstractFetcherThread.scala:172)
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$6$adapted(AbstractFetcherThread.scala:169)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:52)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$5(AbstractFetcherThread.scala:169)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:251)
	at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:169)
	at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:114)
	at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:82)
Caused by: org.apache.kafka.common.KafkaException: Trying to roll a new log segment for topic partition partition-b-97 with start offset 1388 while it already exists.
	at kafka.log.Log.$anonfun$roll$2(Log.scala:1499)
	at kafka.log.Log.maybeHandleIOException(Log.scala:1837)
	at kafka.log.Log.roll(Log.scala:1465)
	at kafka.log.Log.maybeRoll(Log.scala:1450)
	at kafka.log.Log.$anonfun$append$2(Log.scala:858)
	at kafka.log.Log.maybeHandleIOException(Log.scala:1837)
	at kafka.log.Log.append(Log.scala:752)
	at kafka.log.Log.appendAsFollower(Log.scala:733)
	at kafka.cluster.Partition.$anonfun$doAppendRecordsToFollowerOrFutureReplica$1(Partition.scala:589)
	at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:251)
	at kafka.utils.CoreUtils$.inReadLock(CoreUtils.scala:257)
	at kafka.cluster.Partition.doAppendRecordsToFollowerOrFutureReplica(Partition.scala:577)
	at kafka.cluster.Partition.appendRecordsToFollowerOrFutureReplica(Partition.scala:596)
	at kafka.server.ReplicaFetcherThread.processPartitionData(ReplicaFetcherThread.scala:129)
	at kafka.server.ReplicaFetcherThread.processPartitionData(ReplicaFetcherThread.scala:43)
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$7(AbstractFetcherThread.scala:186)
	... 12 more

[ReplicaFetcher replicaId=1006, leaderId=1014, fetcherId=0] Error due to org.apache.kafka.common.KafkaException: Error processing data for partition partition-a-121 offset 29594324
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$7(AbstractFetcherThread.scala:208)
	at scala.Option.foreach(Option.scala:257)
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$6(AbstractFetcherThread.scala:172)
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$6$adapted(AbstractFetcherThread.scala:169)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:52)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$5(AbstractFetcherThread.scala:169)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:251)
	at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:169)
	at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:114)
	at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:82)
Caused by: java.lang.IllegalStateException: Kafka scheduler is not running.
	at kafka.utils.KafkaScheduler.ensureRunning(KafkaScheduler.scala:140)
	at kafka.utils.KafkaScheduler.schedule(KafkaScheduler.scala:110)
	at kafka.log.Log.$anonfun$roll$2(Log.scala:1504)
	at kafka.log.Log.maybeHandleIOException(Log.scala:1837)
	at kafka.log.Log.roll(Log.scala:1465)
	at kafka.log.Log.maybeRoll(Log.scala:1450)
	at kafka.log.Log.$anonfun$append$2(Log.scala:858)
	at kafka.log.Log.maybeHandleIOException(Log.scala:1837)
	at kafka.log.Log.append(Log.scala:752)
	at kafka.log.Log.appendAsFollower(Log.scala:733)
	at kafka.cluster.Partition.$anonfun$doAppendRecordsToFollowerOrFutureReplica$1(Partition.scala:589)
	at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:251)
	at kafka.utils.CoreUtils$.inReadLock(CoreUtils.scala:257)
	at kafka.cluster.Partition.doAppendRecordsToFollowerOrFutureReplica(Partition.scala:577)
	at kafka.cluster.Partition.appendRecordsToFollowerOrFutureReplica(Partition.scala:596)
	at kafka.server.ReplicaFetcherThread.processPartitionData(ReplicaFetcherThread.scala:129)
	at kafka.server.ReplicaFetcherThread.processPartitionData(ReplicaFetcherThread.scala:43)
	at kafka.server.AbstractFetcherThread.$anonfun$processFetchRequest$7(AbstractFetcherThread.scala:186)
	... 12 more