Expected: Exact same configuration and setup works perfectly on prior version (1.9.2), as soon as I upgrade version, NIfi is unable to initialize.
With external zookeeper (cluster_mode) configuration, Nifi is unable to successfully elect leader and stuck in 'Invalid State: The Flow Controller is initializing the Data Flow'.
Logs: (Stuck in Loop)
2019-11-15 17:00:05,991 INFO [main-EventThread] o.a.c.f.state.ConnectionStateManager State change: RECONNECTED
2019-11-15 17:00:05,991 INFO [Curator-ConnectionStateManager-0] o.a.n.c.l.e.CuratorLeaderElectionManager org.apache.nifi.controller.leader.election.CuratorLeaderElectionManager$ElectionListener@256c961a Connection State changed to RECONNECTED
2019-11-15 17:00:06,092 INFO [main-EventThread] o.a.c.f.state.ConnectionStateManager State change: SUSPENDED
2019-11-15 17:00:06,092 WARN [main] o.a.nifi.controller.StandardFlowService There is currently no Cluster Coordinator. This often happens upon restart of NiFi when running an embedded ZooKeeper. Will register this node to become the active Cluster Coordinator and will attempt to connect to cluster again
2019-11-15 17:00:06,093 INFO [main] o.a.n.c.l.e.CuratorLeaderElectionManager CuratorLeaderElectionManager[stopped=false] Attempted to register Leader Election for role 'Cluster Coordinator' but this role is already registered