Problem is solved The problem was a derby.jar on the Applicationserver. Hibernate and this File together results in an Exception. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4045026#4045026 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4045026