OCI-11419
The source PDB "string" must be re-instated as a standby
Cause
An operation was attempted on a pluggable database that was no longer a valid PDB because it was a source for one or more per PDB Data Guard standbys, one of which had been activated as the new primary.
Action
The PDB must be dropped. If a standby is required then create the PDB as a standby using Data Guard Broker. If the PDB is needed to continue as a regular PDB, no longer as part of a Data Guard configuration then it may be unplugged before being dropped and then plugged back in again.