downgrading a 11g database to a previous version
1. Shut down the database and start it up in the downgrade mode.
SQL> startup downgrade
2. Spool the results of the downgrade script.
SQL> spool downgrade.log
3. Execute the downgrade script, called catdwgrd.sql.
4. After the catdwgrd.sql script finished executing, shut down the database cleanly.
SQL> shutdown immediate
5. Start up the database in the upgrade mode, from the pre-upgrade ORACLE_ HOME environment.
SQL> startup upgrade
6. Reload the old PL/SQL packages and data dictionary views.
7. After the reloading of the old packages and views, shut down the database and restart it.
SQL> shutdown immediate SQL> startup
8. Run the utlrp.sql script to recompile any packages, procedures, and types that became invalid during the downgrading of the database.
This completes the downgrading process.
You can run the utlrp.sql script may times. and you should make sure that you handle all invalid objects.