For the jbossas5 app client container, a class loader policy that loads from the child first is used to pickup the client jar manifest references. If such a class loader is registered as the user class loader with the RemotingClassLoader, its not going be delegated to first. This results in duplicate and conflicting classes being loaded. There needs to be an option to delegate to the user class loader before the parent. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4167421#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...