Supported Releases for Downgrading Oracle Database

The downgrade options you have depend on the original Oracle Database release from which the database was upgraded.

Releases Supported for Downgrades

You can downgrade a PDB or CDB from Oracle Database 23ai to Oracle Database 21c or Oracle Database 19c. If you upgraded a non-CDB from 19c and converted to a PDB, you can only downgrade to a PDB on Oracle Database 19c. You can't revert the PDB conversion.

Note:

Starting with Oracle Database 21c, non-CDB architecture is desupported.

The following table provides additional information about releases supported for downgrading. When using this table, also read about compatibility in "Checking for Incompatibilities When Downgrading Oracle Database."

Table 9-1 Supported Releases and Editions for Downgrading

Oracle Database Release or Edition	Downgradable (Yes/No)	Notes
21	Yes	1) Install 21c (21.6) 2) Apply Overlay patch p33809904_216000DBRU_Generic.zip 3) Upgrade the DB from 21c to 23ai 4) Run `catdwgrd.sql` on Target home (23ai) 5) Run catrelod.sql on Source home (21c) 6) Run utlrp.sql on Source home (21c)
19	Yes	No additional information at this time.
Oracle Enterprise Manager	No	If you downgrade to an earlier supported release, then you must reconfigure Oracle Enterprise Manager controls. Before you start your upgrade, you must use the `emdwgrd` utility to save DB Control files and data, so that you can restore Oracle Enterprise Manager Database Control (DB Control) after a downgrade.
Oracle Database Express Edition	No	You cannot downgrade a database that is upgraded from Oracle Database Express Edition.

Recommendations to Review Before Downgrading

Before you start the downgrade procedure, Oracle recommends that you install the latest Release Update in both Oracle homes (the one that you downgrade from, and the one to which you downgrade) before you downgrade a CDB, or before you unplug and downgrade a PDB.

The latest Release Update Patches are available for download on My Oracle Support. Review "Primary Note for Database Proactive Patch Program (Doc ID 888.1)" on My Oracle Support for your release.

The minimum compatibility setting for Oracle Database 23ai is 19. You cannot downgrade to releases earlier than the minimum compatibility setting for the new Oracle Database release.

The following recommendations for earlier supported releases affect downgrading for Oracle Database:

Multitenant architecture provides architecture features for a multitenant container database (CDB), and pluggable databases (PDBs). If you are upgrading to multitenant architecture, and you set the compatible initialization parameter to the highest level after upgrading to this release, then you cannot downgrade the database after an upgrade.
Downgrade is not supported for Oracle Enterprise Manager. If you downgrade to an earlier supported release, then you must reconfigure Oracle Enterprise Manager controls.