Hi and thanks for your answer. Currently all my Hibernate libraries (Core, Annotations and EntityManager) are packaged in my EAR root - this packaging seems to be working fine on other app servers. Is the conflict due to the presence of the hibernate3.jar and jboss-hibernate.jar files in the ${JBOSS_HOME}/server/default/lib directory? And is this previous directory the "lib" directory you're mentioning in your message? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3981659#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...