db816628_Data_Guard_11g___Using_DBMS_DG__Description
[Error] ORA-16820: Fast-Start Failover observer is no longer observing this database [Description] 
DBMS_DG.INITIATE_FS_FAILOVER was invoked but the configuration detects that the observer may not be running.
Mahir M. Quluzade | Oracle Blog: Oracle Data Guard 11g – Using DBMS_DG
Description