Location of DBMS_SERVICES logs

Hi all,

On one instance, I have multiple services where users can connect from the web page of the application, from the sql developer client or from the administration console of the application.

Since we upgraded the oracle database from 12g to 19.12, there is some unexpected error on the dbms_services. During the night, where the production plan of the application is running, the services are stopping unexpectedly.

We bypassed the errors by placing scripts that start the services. We first suspected that the database was restarted during the night but it doesn't. Thus, I would like to have some logs of the dbms_services to help me get the root cause of the error.