Taking another tact, I got and built 1.4.1.GA source and compared the generate jboss-messaging.sar between 1.4.1 and 1.4.2 - they are the same. So the steps to update AS 5.0.0.GA to Messaging 1.4.2 should be copying jboss-messaging-client.jar to the client directory and jboss-messaging.jar to the common/lib directory. I did that and my messaging clients are working. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4207455#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...