For supported releases of Oracle Database, you can downgrade a database to the release from which you last upgraded.

• Supported Releases for Downgrading Oracle Database
  The downgrade options you have depend on the original Oracle Database release from which the database was upgraded.
• Prepare to Downgrade a Standby Database with the Primary
  If you are using an Oracle Data Guard Standby database, then review the procedure you can use to downgrade the standby database with the primary database
• 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.
• Perform a Full Backup Before Downgrading Oracle Database
  Oracle strongly recommends that you perform a full backup of your new Oracle Database release before you downgrade to a supported earlier release.
• Using Scripts to Downgrade Oracle Database 23ai
  To automate downgrades, Oracle provides the dbdowngrade utility script. When necessary, you can also continue to run catdwgrd.sql manually, as in previous releases.
• Downgrading a Single Pluggable Oracle Database (PDB)
  If you are downgrading Oracle Database, then you can downgrade one PDB without downgrading the whole CDB.
• Downgrading PDBs That Contain Oracle APEX
  Use this procedure to avoid INVALID OBJECTS OWNED BY APEX_050000 errors when you downgrade PDBs that contain Oracle APEX (formerly Application Express).
• Post-Downgrade Tasks for Oracle Database Downgrades
  After you downgrade your Oracle Database release, you can be required to complete additional tasks, due to changes that affect compatibility, components, and supported protocols.
• Troubleshooting the Downgrade of Oracle Database
  Use this troubleshooting information to address issues that may occur when downgrading Oracle Database.