We have used javassist 3.8.0.GA in AS 4.2.3.GA without problems. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4172850#4172850 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4172850