While connecting to catalog and running rman script, you may face below error.
RMAN-06429: TARGET database is not compatible with this version of RMAN
RMAN-06618: RMAN client and database release mismatch; indicated database release is 12.1.0.2
rman target sys/oracle@TESTDB catalog cat_user/pwd@CATDB2. Upgrade catalog:
RMAN> upgrade catalog; recovery catalog owner is RMAN_SEC58_6 enter UPGRADE CATALOG command again to confirm catalog upgrade RMAN> upgrade catalog;