Hello @Vinosh
Thanks you for the logs, Hope you don’t mind I edited your post so its easier to read. perhaps check it out here
From what I see the issue is that Graylog is probing for the ES version used on startup. It goes through the list of configured nodes and gives up if none of them are up. Can you make sure that ES is available before GL is starting up? If not, you can set the elasticsearch_version configuration setting to 7.
If that doesn’t work then here are some more suggestions you could use to troubleshoot this issue.
Have you tried curl command to check Elasticsearch cluster? You may have to adjust it to your environment.
ES Health check
curl -XGET http://es_node:9200/_cluster/health?pretty
Check Nodes
curl -XGET http://es_node:9200/_nodes?pretty
curl -XGET http://es_node:9200/_cat/nodes?v
If so what do you see?