When you switched to 4.2.3, did you also change your client's classpath to include the 4.2.3 client JARs? View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4232842#4232842 Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&p=4232842