Oracle Database 19c -- Hot to Enable Trace for the Scheduler Coordinator

Problem

You want to enable trace for the dbms scheduler coordinator process (CJQ0) for investigating issues with dbms scheduler jobs

Solution

To enable trace for the CJQ0 process execute the command at cdb$root level:

SQL> alter system set events '27402 trace name context forever, level 255'; 

Note. For wider tracing use level 65535

To disable tracing:

SQL> alter system set events '27402 trace name context off';