OCI ExaCS Database Upgrade Rollback

Recently I was testing OCI database upgrade from 12c to 19c and ran into an issue I wanted to fix. I was doing this via dbaascli (on Exadata) and the upgrade hit Bug 34455245 – db12c upgrade to 19c fails with ORA-600 [kxhfmgetextent.1] (Doc ID 34455245.8). I tried few things as with dbaascli you can…