Thank you for your very prompt response! I believe I have already resolved the classpath issue with respect to jboss-remoting.jar by removing the remoting classes from jbossall-client.jar (this appears to be the recommended solution in Tomcat where it is otherwise difficult to control classpath order) but I have not done anything similar for any conflicts between jboss-messaging-client.jar and jbossall-client.jar. The messaging user guide makes no mention of possible conflicts between these latter two jars and an inspection of them shows no overlapping packages. I am using jboss-remoting version 2.2.3 (upgraded on the server) and have experimented with both the 2.2.3 and 2.2.3-brew on the client. Are you using jboss-aop-1.5.6.GA? The messaging guide says to use 2.0.1.GA but this throws errors with AS 4.2.3. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4256423#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...