Oracle: ORA-12712: new character set must be a superset of old character set

To change the character set of  database , we have to follow  following steps:

1. Shut down the database, using either a SHUTDOWN IMMEDIATE or a SHUTDOWN NORMAL statement.

2. Do a full backup of the database because the ALTER DATABASE CHARACTER SET statement cannot be rolled back.

3. Startup Oracle database

SQL> startup mount;

SQL> ALTER SYSTEM ENABLE RESTRICTED SESSION;

SQL> ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;

SQL> ALTER SYSTEM SET AQ_TM_PROCESSES=0;

SQL> ALTER DATABASE OPEN;

SQL> ALTER DATABASE CHARACTER SET AL32UTF8;

If you get the error ORA-12712, please update the following table.

"ORA-12712: new character set must be a superset of old character set"