You have a not-null constraint on the status_ field, so i would check to see why the object you're merging has status_=null. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4046359#4046359 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4046359