Kafdrop unable to access topic details: Unable to get partition log size for topic twitter.demo partitions

[darienrrushi]

Kafka broker 10. Kafdrop was working fine for quite some time with this broker and zookeeper 3.4.5.
Suddenly it is not able to view topic details and messages. It is able to get a list of all the topics available however but not things like offsets, lag, available messages. The following is printed in the Kafdrop log when attempting to access a topic from the UI.
Any pointers?

[2017-04-14 22:48:45.613]  - 19507 ERROR [ForkJoinPool-1-worker-10] --- CuratorKafkaMonitor: Unable to get partition log size for topic twitter.demo partitions (0,1)
java.nio.channels.ClosedChannelException
	at kafka.network.BlockingChannel.send(BlockingChannel.scala:100)
	at com.homeadvisor.kafdrop.service.CuratorKafkaMonitor.lambda$null$47(CuratorKafkaMonitor.java:821)
	at com.homeadvisor.kafdrop.util.BrokerChannel.execute(BrokerChannel.java:52)
	at com.homeadvisor.kafdrop.service.CuratorKafkaMonitor.lambda$sendOffsetRequest$48(CuratorKafkaMonitor.java:819)
	at org.springframework.retry.support.RetryTemplate.doExecute(RetryTemplate.java:276)
	at org.springframework.retry.support.RetryTemplate.execute(RetryTemplate.java:157)
	at com.homeadvisor.kafdrop.service.CuratorKafkaMonitor.sendOffsetRequest(CuratorKafkaMonitor.java:816)
	at com.homeadvisor.kafdrop.service.CuratorKafkaMonitor.lambda$null$43(CuratorKafkaMonitor.java:760)
	at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
	at java.util.HashMap$EntrySpliterator.forEachRemaining(HashMap.java:1691)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
	at java.util.stream.ReduceOps$ReduceTask.doLeaf(ReduceOps.java:747)
	at java.util.stream.ReduceOps$ReduceTask.doLeaf(ReduceOps.java:721)
	at java.util.stream.AbstractTask.compute(AbstractTask.java:316)
	at java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:731)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinTask.doInvoke(ForkJoinTask.java:401)
	at java.util.concurrent.ForkJoinTask.invoke(ForkJoinTask.java:734)
	at java.util.stream.ReduceOps$ReduceOp.evaluateParallel(ReduceOps.java:714)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:233)
	at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
	at com.homeadvisor.kafdrop.service.CuratorKafkaMonitor.lambda$getTopicPartitionSizes$44(CuratorKafkaMonitor.java:789)
	at java.util.concurrent.ForkJoinTask$AdaptedCallable.exec(ForkJoinTask.java:1424)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

[darienrrushi]

Resolved ... the issue was somewhere else. Firewalld was preventing Kafdrop from connecting to the broker.