For backing up the Solr indexes using the Alfresco Share Admin Console or the alfresco-global.properties file, or JConsole, see Backing up Search Services.
To restore the backup successfully, the contentstore directory and database must be backed up as a set. When you restore an Alfresco backup, you must restore both the Alfresco database and the dir.root directory (contentstore directory) from the same backup set. Otherwise, the repository may be corrupted.
The dir.root directory is defined in the alfresco-global.properties file. By default, this directory is named alf_data and is located within the directory where Alfresco Content Services is installed.
Cause: It occurs because the cloned node contains the cluster id from production and tries to join that cluster.
Solution: To avoid the problem you should ensure any cloned nodes required for upgrade testing are network isolated from the production nodes.