java.lang.IllegalArgumentException: Can't convert argument: null

Problem

java.lang.IllegalArgumentException: Can't convert argument: null

I got this exception when I was trying to run a JEE web application in tomcat 6 using ECLIPSE IDE.

Problem Cause
I noticed that my web.xml file contained many "javaee:" tags although the namespace for javaee was already defined at < web-app >  level as xmlns="http://java.sun.com/xml/ns/javaee"

Solution

This is the first time I noticed these javaee tags in a web.xml so I got rid of those , and tried to run the application again on tomcat this time it is working fine.

The below stackoverflow thread has some good details about it

http://stackoverflow.com/questions/2293797/tomcat-startup-web-xml-issue