While promoting auto-discovered targets in OEM 13.4, the following errors occur:
“ORA-20411: Monitoring credentials not set for target name RACTESTDB target type rac_database set nameDBCredsMonitoring”
After testing monitoring user DBSNMP credentials , all works fine.
WORKAROUND
Remove the auto discovered targets, and manually add them into OEM again by :
Setup -> Add Target -> Add Targets Manually -> Add Using Guided Process
Make DBA Life Easy 