Oracle Database 19c -- Enable LREG Process Trace

Problem

You want to enable tracing for LREG process to identify the issues with dynamic registration of services with the listener

Solution

To enable tracing: 

alter system set events 'trace[LREG] disk highest';

alter system set events = 'immediate trace name LREG_STATE level 3';

To disable tracing:

alter system set events 'trace[LREG] disk disable';