A is correct: applications need to fail over to the new CDB
B is correct: Platform and Character Set Prerequisites https://docs.oracle.com/en/database/oracle/oracle-database/21/multi/relocating-a-pdb.html#GUID-F887DBA7-61A6-49FB-8400-40632765F1E1
C is not correct, downtime is required: Using PDB Relocation to Upgrade an Individual PDB (Doc ID 2771716.1) https://support.oracle.com/knowledge/Oracle%20Database%20Products/2771716_1.html
D is not correct, downgrade is not supported.
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Datajimm
1 month, 3 weeks agoGiorgioGss
9 months, 2 weeks ago