When the oracle connector registration occurs, it runs a query like

SELECT MAX(TIMESTAMP_TO_SCN(last_ddl_time)) from all_objects where owner = 'USER'

This is running timestamp_to_scn on all ddl times, which is unnecessary from a performance perspective as well as can lead to errors like

Caused by: java.lang.RuntimeException: java.sql.SQLException: ORA-08180: no snapshot found based on specified time
ORA-06512: at "SYS.TIMESTAMP_TO_SCN", line 1

when the snapshots don't exist. This is particularly obvious when it's a pre-existing database with changes from long ago.

Proposal would be to change the query to

SELECT TIMESTAMP_TO_SCN(MAX(last_ddl_time)) from all_objects where owner = 'USER'

Which will call timestamp_to_scn on only the last change.