Message Oracle RMAN-08591 - WARNING: invalid archived log deletion policy

ERRORWARNING: invalid archived log deletion policy
CAUSEAn invalid ARCHIVELOG DELETION POLICY was supplied. The archived log deletion policy was APPLIED but there was no mandatory archived log destinations.
ACTIONOne of the following: 1) Change archived log deletion policy using CONFIGURE command 2) Make one or more of standby destination as MANDATORY.