Oracle Error Message
ORA-16076: unknown standby database destination
Reason for the Error
A standby database destination was specified that was not accessed by another instance. If the initialization parameter LOG_ARCHIVE_CONFIG does not define a DG_CONFIG, this mismatch may be due to a standby database having been restarted recently.
Solution
Ensure that at each instance the set of standby databases referred to by LOG_ARCHIVE_DEST_n initialization parameters is the same and define a DG_CONFIG at each instance to identify those databases explicitly.