When I downgraded Elasticsearch 7.10 to 7.6, I was not able to restart the elasticsearch service and was facing these errors: and “Format version is not supported” After diagnosing the issue and going through a number of web URLs, I come to know that the following line in the elasticsearch.yml file will fix my issue. cluster.initial_master_nodes: ["x.x.x.x"] OR cluster.initial_master_nodes: master - node - a I hope it will help someone and save their time too. Thanks!!! Enjoy Programming!! :)
In case you have upgraded elastic search by mistake and want to rollback to the previous working version, here are the steps. In my case, I upgraded the ElasticSearch to 7.9.2-1 and wanted to rollback to 7.6.2-1 1. yum downgrade elasticsearch-7.6.2-1 2. Restart elasticsearch sudo service elasticsearch start I hope it will work but in case you are facing any of the following issues, please run respective comments. Errors: Problem . Unable to create temporary keystore at [/etc/elasticsearch/elasticsearch.keystore.tmp] Solution : sudo -u elasticsearch -s /usr/share/elasticsearch/bin/elasticsearch-keystore create Problem : Likely root cause: java.nio.file.AccessDeniedException: /etc/elasticsearch Solution : chmod g+w /etc/elasticsearch Thanks!! Enjoy Programming! Reference Links ==================================== https://discuss.elastic.co/t/unable-to-create-temporary-keystore-at-etc-elasticsearch-elasticsearch-keystore-tmp/136411