Can you post the final persistence.xml file(after the modifications) that you are using? Also have you changed anything in the JBoss installation after downloading it? And can you reproduce this behaviour without your application deployed and only the datasource deployed? Finally do you have any jndi.properties packaged in your application? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4159490#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...