Tomcat 6+: Infamous "SEVERE: Error listenerStart" message - How-To debug this error?

I’m sure if you have been developing with Java and Tomcat for sometime, you are likely to run into the infamous debug error. SEVERE: Error listenerStart You will most likely start Googling it trying to find out what the heck is going on. And in trying to see the extended logging on what that “listenerStart” error means. After some lucky searches, you will see links asking you to drop a “log4j.