ORA-16642: db_unique_name mismatch
Cause: The expected db_unique_name value did not match the actual db_unique_name value for the database that the broker contacted using the connect identifier that was associated with that database.
Action: Verify that the connect identifier correctly connects to the intended database. Verify that the name of the database that the broker expects to find via that connect identifier matches the actual db_unique_name for that database.