Pega 23 and 24 officially support Oracle 19c as the database, which is a long-term support version from Oracle. Oracle 21c is an innovation release and not long-term support, so it is not officially listed or recommended by Pega for production use. Even though Oracle 21c might work technically, it is not tested or certified by Pega, which means any issues related to it may not be supported. Pega’s support documents and platform guides only mention Oracle 19c. For safe and stable use, it is better to stick with Oracle 19c when using Pega 23 or 24. If needed, you can also contact Pega support (GCS) for confirmation