Known catalog backup limitation
Mixed versions of NetBackup in the backup environment is supported. Limitations exist, however, when you back up the NetBackup catalog.
If the primary server performs catalog backups to a separate media server, that media server must use the same version of NetBackup as the primary server. Since the NetBackup catalog resides on the primary server, the primary server is considered to be the client for a catalog backup.
As such, the media server must have the same version of NetBackup as the primary server.
Failure to use the same version of NetBackup on the media server results in improperly protected catalog data.
More information on mixed version support is available.