Data Guard Setup error from auxiliary database: ORA-17640/17627 RMAN-06136

Hello, I am looking to set up a Physical Standby, using 18.3.0.0 Database Enterprise Edition running on Windows 2016

I've set up data guard many successfully before would usually set up something like: Primary:                                    Standby

db_name = db1                              db_name = db1

db_unique_name = db1                       db_unique_name = db1_sby

This works fine.

However, sometimes, we switch roles and I would like to name each side with the geographical name. I understand that the db_name always has to be same / constant across Primary and Standby.

As a variation on the above, I am looking to use a different db_unique_name from the db_name on the Primary, because in our environment, the Primary may not always be that and it gets confusing if we switch.