I’m encountering an issue when attempting to restart one of the nodes in my ZooKeeper ensemble. Despite trying various solutions found online, including starting the nodes one by one according to their IDs, I’m still getting errors. Specifically, when trying to get the server status using ‘echo stat | nc localhost 2181’, I receive the message “This ZooKeeper instance is not currently serving requests”. Additionally, connecting to zkcli also fails, displaying the following error:

2024-05-08 10:00:12,241 [myid:localhost:2181] - INFO  [main-SendThread(localhost:2181):o.a.z.ClientCnxn$SendThread@1164] - SASL config status: Will not attempt to authenticate using SASL (unknown error)
2024-05-08 10:00:12,242 [myid:localhost:2181] - INFO  [main-SendThread(localhost:2181):o.a.z.ClientCnxn$SendThread@998] - Socket connection established, initiating session, client: /0:0:0:0:0:0:0:1:45772, server: localhost/0:0:0:0:0:0:0:1:2181
2024-05-08 10:00:12,245 [myid:localhost:2181] - WARN  [main-SendThread(localhost:2181):o.a.z.ClientCnxn$SendThread@1285] - Session 0x0 for server localhost/0:0:0:0:0:0:0:1:2181, Closing socket connection. Attempting reconnect except it is a SessionExpiredException.
org.apache.zookeeper.ClientCnxn$EndOfStreamException: Unable to read additional data from server sessionid 0x0, likely server has closed socket
    at org.apache.zookeeper.ClientCnxnSocketNIO.doIO(ClientCnxnSocketNIO.java:77)
    at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:350)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1274)

I’d appreciate any guidance on the correct way to restart a node in a ZooKeeper ensemble.
I’ve also verified that the ports are listening.
No entries were logged in the Zookeeper logs.