I get this exception everytime I try to delete an entity. There is a many-to-many reference within this entity. Before deleting an entity, I delete the references, which works fine. But the entity itself won't delete. The same exception appears when deleting entities that have no references at all. So I don't know where this comes from and how to solve. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4220090#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...