https://community.cloudera.com/t5/Support-Questions/Issue-with-NiFi/m-p/151625#M114104 <P><A rel="user" href="https://community.cloudera.com/users/525/mclark.html" nodeid="525">@Matt</A> </P><P>Just got the error "<EM><STRONG>An unexpected error has occurred. Action was performed, but no nodes are connected.</STRONG></EM>" while working with a flow. The flow simply takes log files and put in HDFS. NiFi went dead at the point of putting the files in HDFS. The file sizes are less than 150MB and there are only 24 of them.</P><P>I have restarted the cluster and it's back up...</P><PRE>2017-01-31 12:01:42,731 ERROR [Leader Election Notification Thread-4] o.a.c.f.recipes.leader.LeaderSelector The leader threw an exception java.lang.InterruptedException: null at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(AbstractQueuedSynchronizer.java:1326) ~[na:1.8.0_77] at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:277) ~[na:1.8.0_77] at org.apache.curator.CuratorZookeeperClient.internalBlockUntilConnectedOrTimedOut(CuratorZookeeperClient.java:325) ~[curator-client-2.11.0.jar:na] at org.apache.curator.RetryLoop.callWithRetry(RetryLoop.java:106) ~[curator-client-2.11.0.jar:na] at org.apache.curator.framework.imps.DeleteBuilderImpl.pathInForeground(DeleteBuilderImpl.java:240) ~[curator-framework-2.11.0.jar:na] at org.apache.curator.framework.imps.DeleteBuilderImpl.forPath(DeleteBuilderImpl.java:225) ~[curator-framework-2.11.0.jar:na] at org.apache.curator.framework.imps.DeleteBuilderImpl.forPath(DeleteBuilderImpl.java:35) ~[curator-framework-2.11.0.jar:na] at org.apache.curator.framework.recipes.locks.LockInternals.deleteOurPath(LockInternals.java:339) ~[curator-recipes-2.11.0.jar:na] at org.apache.curator.framework.recipes.locks.LockInternals.releaseLock(LockInternals.java:123) ~[curator-recipes-2.11.0.jar:na] at org.apache.curator.framework.recipes.locks.InterProcessMutex.release(InterProcessMutex.java:154) ~[curator-recipes-2.11.0.jar:na] at org.apache.curator.framework.recipes.leader.LeaderSelector.doWork(LeaderSelector.java:425) [curator-recipes-2.11.0.jar:na] at org.apache.curator.framework.recipes.leader.LeaderSelector.doWorkLoop(LeaderSelector.java:441) [curator-recipes-2.11.0.jar:na] at org.apache.curator.framework.recipes.leader.LeaderSelector.access$100(LeaderSelector.java:64) [curator-recipes-2.11.0.jar:na] at org.apache.curator.framework.recipes.leader.LeaderSelector$2.call(LeaderSelector.java:245) [curator-recipes-2.11.0.jar:na] at org.apache.curator.framework.recipes.leader.LeaderSelector$2.call(LeaderSelector.java:239) [curator-recipes-2.11.0.jar:na] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_77] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_77] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_77] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_77] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_77] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_77] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [na:1.8.0_77] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_77] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_77] at java.lang.Thread.run(Thread.java:745) [na:1.8.0_77] </PRE> Tue, 31 Jan 2017 19:23:36 GMT joshua_adeleke 2017-01-31T19:23:36Z