Fix NodeNotConnectedException

✅ Solution

The "NodeNotConnectedException" in Elasticsearch usually means the client is trying to communicate with a node before the node has fully joined the cluster or before the client has established a connection. To fix it, implement a retry mechanism with exponential backoff on client operations, especially during startup, to give Elasticsearch nodes time to initialize and ensure the client properly discovers and connects to the cluster. Also, verify the cluster health is green before executing critical operations.