Oracle Message RMAN-06429 - string database is not compatible with this version of RMAN

ERRORstring database is not compatible with this version of RMAN
CAUSEThe indicated database is not compatible with this version of the Recovery Manager (RMAN). Other messages have also been issued which detail the cause of the error.
ACTIONSee the other messages. If the database is CATALOG, then you may be able to use the CREATE CATALOG or UPGRADE CATALOG commands to correct the problem. If the database is TARGET or AUXILIARY, then you must either upgrade the target database or use a newer version of the RMAN executable.