Oracle Migration and Upgrade from 12c to 19c using RMAN Incremental Backups 

Oracle Migration and Upgrade using RMAN Incremental Backups level 0 and level 1 to minimize the downtime as much as possible.
The last step error come because of bug :
Database Upgrade to 12.2, 18c, 19c fails with ORA-01422, ORA-06512 for SYS.DBMS_STATS (Doc ID 2525596.1)