Did you declare persistence-unit element in your persistence.xml? i.e., | <persistence> | <persistence-unit name="phx4EJB"> | <jta-data-source>java:/MySqlDS</jta-data-source> | <properties> | . . . . . | </properties> | </persistence-unit> | </persistence> | | It seems like you are telling your PersistenceContext, pointing it to persistence-unit phx4EJB @PersistenceContext(unitName="phx4EJB") , but EJB3 deployer can not find it. I was able to replicate it by doing just that. Regards Oleg Zhurakousky View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3960843#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...