Upgrades with Oracle Data Guard where you want to uprade a non-CDB to a PDB, and reuse the non-CDB stadnby datafiles require a special procedure.

When you have an Oracle Data Guard deployment on your non-CDB source Oracle Database configuration, and you want to reuse the source standby database files on your target PDB after you plug the non-CDB in as a PDB into the primary database of an Oracle Data Guard configuration, there are particular steps required that you must perform manually. For the current release of AutoUpgrade, this functionality is not supported.

For instructions on how to complete an upgrade with this scenario, refer to Reusing the Source Standby Database Files When Plugging a non-CDB as a PDB into the Primary Database of a Data Guard Configuration (Doc ID 2273304.1)