I can reproduce the issue by killing the java processes associated with the cluster coordinator node.
The NiFi UI will not be accessible anymore until that particular node is brought up again, or until the node entry is removed from the cluster (via the REST API). Killing non-coordinator nodes does result in nifi detected heartbeat loss and flagging it as DISCONNECTED. -- View this message in context: http://apache-nifi-users-list.2361937.n4.nabble.com/Nifi-Cluster-fails-to-disconnect-node-when-node-was-killed-tp1942p1947.html Sent from the Apache NiFi Users List mailing list archive at Nabble.com.
