ORA-00439: feature not enabled: Flashback Database

Error Description:
-------------------
While trying to enable flashback feature the error comes.
SQL> alter database flashback on;
alter database flashback on
*
ERROR at line 1:
ORA-00439: feature not enabled: Flashback Database

Error Explanation:
--------------------

Some feature is is not enabled in oracle database standard edition or Oracle database Standard Edition One. The most common feature is Real Application Clusters, Online index maintenance, Online table organization, Online table redefinition, Block-level media recovery,Parallel backup and recovery,Point-in-time tablespace recovery ,RMAN Backup Encryption, Unused Block Compression, Oracle Flashback Table, Oracle Flashback Database, Oracle Flashback Transaction Query, Restore Points.

So flashback database is disabled in standard edition or in standard one edition. To be able to flashback on you have to use enterprise edition.

You can check from,
Version:
---------
1)SQL> SELECT * FROM V$VERSION;

To know the options enabled in your database,

2)SQL> SELECT * FROM V$OPTION;