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.
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!