RMAN Catalog Upgrade to Oracle 188.8.131.52
It sounds so simple - but in this specific case a bit of doc reading is required as upgrading the RMAN catalog to handle Oracle 184.108.40.206 databases is not as trivial as in the past.
Thanks to a German customer and a friendly colleague from Sales Consulting in Stuttgart I have learned my RMAN lesson for Oracle Database 220.127.116.11 this week. A simple "upgrade catalog" is not the correct step once you'd like to handle backups of Oracle 18.104.22.168 databases in your current catalog schema.
Even though you may not have ever heard before about Virtual Private Catalogs you need to follow this guideline:
The doc tells you to run this step first:
$ rman CATALOG my_catalog_owner@catdb
recovery catalog database Password:
RMAN> UPGRADE CATALOG;
It should work now
Referances link: https://blogs.oracle.com/UPGRADE/entry/rman_catalog_upgrade_to_oracle