I have done few analysis from Logs where in exactly node went down at 8:56 AM EST First error - Failed to send heartbeat due to: org.apache.nifi.cluster.protocol.ProtocolException: Failed marshalling 'HEARTBEAT' protocol message Second error - Cluster failed processing request: org.apache.nifi.cluster.exception.NoClusterCoordinatorException: No node has yet been elected Cluster Coordinator. Cannot establish connection to cluster yet.. Returning Service Unavailable response. Third error - Disconnecting node due to Failed to properly handle Reconnection request due to org.apache.nifi.controller.serialization.FlowSynchronizationException: Failed to connect node to cluster because local flow controller partially updated. Administrator should disconnect node and review flow for corruption. Fourth error - Node disconnected due to Failed to properly handle Reconnection request due to org.apache.nifi.controller.serialization.FlowSynchronizationException: Failed to connect node to cluster because local flow controller partially updated. Administrator should disconnect node and review flow for corruption. ... View more