While connecting to catalog and running rman script, you may face below error.

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

Solution:

Upgrade the catalog database as below.

1 . Connect to catalog database

rman target sys/oracle@TESTDB catalog cat_user/pwd@CATDB

2. Upgrade catalog:
RMAN> upgrade catalog;

recovery catalog owner is RMAN_SEC58_6
enter UPGRADE CATALOG command again to confirm catalog upgrade

RMAN> upgrade catalog;