@Sanga  What reason is being logged by the elected cluster coordinator node when node-0 gets initially disconnected?  Is it a lack of heartbeat? I understand that onc it gets initially disconnected, NiFi cluster coordinator requests that it reconnect on next heartbeat and the triggered flow synchronization result in a exception blocking the node from rejoining the cluster. My initial thought is  that you may be hitting NIFI-12969 or NIFI-12232 which was addressed in Apache NiFi 1.26.  An upgrade may help with your issue.   Please help our community grow. If you found any of the suggestions/solutions provided helped you with solving your issue or answering your question, please take a moment to login and click "Accept as Solution" on one or more of them that helped. Thank you, Matt ... View more

@Sanga  What is the specific Apache NiFi version being used? Any disk space issues on Node-0? Any other exceptions in the NiFi logs? Logs shared cover the reconnection attempt.  What was the reason given for the node disconnection? Thank you, Matt ... View more