Check COMPATIBLE Parameter when Downgrading Oracle Database

If COMPATIBLE has been changed after the upgrade, then it is no longer possible to downgrade an Oracle Database.

If you have updated the COMPATIBLE parameter to set the compatibility level of your Oracle Database release to the current release, then you are not able to downgrade to an earlier release. This issue occurs because new releases have changes to the Data Dictionary, and can have other feature changes that prevent downgrades.

To check the COMPATIBLE parameter setting for your database before you downgrade, enter the following command:

SQL> SELECT name, value, description FROM v$parameter WHERE name =
    ‘compatible’;

Note:

New installations of Oracle Database 23ai Release Update 23.6 automatically update the COMPATIBLE parameter setting to 23.6.

For Oracle ASM disk groups, if you changed the compatible.asm parameter after the upgrade to the upgraded release value, then when you downgrade to the earlier release, you cannot mount your Oracle ASM disk groups. The value for compatible.asm sets the minimum Oracle ASM release that can mount a disk group.

As part of your downgrade, you must create a new disk group to your downgraded release level, and restore data to that downgraded compatibility ASM disk group.

Parent topic: Downgrading Oracle Database to an Earlier Release