kibana server is not ready yet
Kibana web ui is failed with the above error. The following logs found in the startup logs of Kibana service.
"message":"Another Kibana instance appears to be migrating the index. Waiting for that migration to complete. If no other Kibana instance is attempting migrations, you can get past this message by deleting index .kibana_1 and restarting Kibana."
Deleting .kibana* indexes will fix the problem,
#curl --request DELETE 'elastic-search-host:9200/.kibana*'
Where elastic-search-host need to be replaced with the hostname or ipaddress of the elastcsearch server.
Then restart the Kibana service.
#systemctl restart kibana