db816628_Data_Guard_11g___Using_DBMS_DG__Description
[Error] ORA-16666: unable to initiate Fast-Start Failover on a standby database [Description] 
DBMS_DG.INITIATE_FS_FAILOVER was invoked on a standby site.
Mahir M. Quluzade | Oracle Blog: Oracle Data Guard 11g – Using DBMS_DG
Description