Oracle RDS, 19 non-pdb to 21 PDB upgrade

19c is a long term support release, support available through:

• April 30, 2024 without Extended Support or an Unlimited License Agreement
• April 30, 2027 with Extended Support or an Unlimited License Agreement

RDS for Oracle major versions remain available at least until the end of support date for the corresponding Oracle Database release version. Before we ask that you upgrade to a newer major version and to help you plan, we provide a reminder at least 12 months in advance. We do so to communicate the detailed upgrade process If Amazon extends support for an RDS for Oracle version for longer than originally stated, we plan to update the table to reflect the later date which can verified at: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_UpgradeDBInstance.Oracle.Overview.html

Yes , starting Oracle 21c all database are CDB's. You can convert an Oracle Database 19c non-CDB to a CDB, but you can't convert a CDB to a non-CDB. You can only upgrade a CDB to a CDB. You can perform the same by going to AWS RDS Console -> Choose your non CDB instance -> Click Modify -> Change architecture settings to Multitenant architecture. There are certain limitations which includes :-

• You cant convert CDB to Non-CDB.
• You cant perform upgrade and modification in same operation.
• DB with Data guard enabled cant be modified to CDB.