ORA-16478: cannot locate far sync instance connect string
Cause:
The connect string for the far sync instance that is flagged as the source of live redo for this database could not be located.
Action:
Define a LOG_ARCHIVE_DEST_n parameter for the far sync instance using the SERVICE attribute to define the connect string for the far sync instance destination. This destination should be set to DEFER using the corresponding LOG_ARCHIVE_DEST_STATE_n parameter. Once the connect string is defined, retry the failover operation. Using the FORCE option on the failover command allows the operation to proceed and bypass the far sync instance but bypassing the far sync instance increases the potential for data loss.