Fix MasterNotDiscoveredException

✅ Solution

MasterNotDiscoveredException in Elasticsearch usually indicates that the master node election has failed, often due to network connectivity issues or insufficient resources allocated to the master-eligible nodes. To fix this, ensure that all master-eligible nodes can communicate with each other by checking network configurations and firewall settings, and increase the `discovery.seed_hosts` configuration to include all master-eligible nodes' addresses or hostnames explicitly. Also, check resource utilization (CPU, memory) on master-eligible nodes and increase if necessary to avoid performance bottlenecks during node discovery and election.