Hi, I certainly did copy over the EAR file into the deploy folder. What I meant was I did not copy any third parties jars into my JBoss.5.0.0.GA lib/deploy folder. The error only appears if i deploy one of my application jar. If i remove the problematic jar, i do not get the exception but other jars depends on the removed jar so I get a ClassNotFoundException. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4254615#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...