I encountered similar problem, solved it and it might be of some help to someone else. The cause was gwt-dev-linux jar deployed with the problematic war. gwt-dev-linux contains some of catalina classes which were out of version for my jboss instance. So grep the libs deployed with your war on the catalina classes and get all the junk out of your war :-). Vasek View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4090661#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...