When I try to log on, I see an error message "ServletException: NLIC/0" and cannot continue.

The issue seems to be related to WombatDialer not being able to initialize its environment properly, and this is usually caused by the JVM not being able to detect the current network configuration. This seems to be a transient issue and can easily be fixed by issuing a: /etc/init.d/qm-tomcat6 restart and accessing the system again.

If you already upgraded to WombatDialer 18.08, and the issue is still not solved, consult this FAQ: After upgrading to WombatDialer 18.08, I see the error message "ServletException: NLIC/0"