Do not delete the jar files from the server's lib folder. Post the contents of your jboss-app.xml, where you have configured the classloader for your application. Also post the exception stacktrace when you deploy your application with these configurations. In your ear file which are the hibernate jar files that you have and also where are they placed in the ear? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4120528#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...