ORA-38707
Tried to enable flashback of whole database, but it failed with ORA-38706 and ORA-38707.
SQL> alter database flashback on;
alter database flashback on
*
ERROR at line 1:
ORA-38706: Cannot turn on FLASHBACK DATABASE logging.
ORA-38707: Media recovery is not enabled.
ORA-38707 means that media recovery is needed to support database flashback, which needs archivelog mode to be enabled.
Solution
The solution is to enable archivelog mode first, then enabling the whole database flashback.
SQL> shutdown immediate;
SQL> startup mount;
SQL> alter database archivelog;
Database altered.
SQL> alter database flashback on;
Database altered.
SQL> select flashback_on from v$database;
FLASHBACK_ON
------------------
YES
SQL> alter database open;
Database altered.