Thanks for nothing, folks. For the sake of other poor souls having this problem: It can be solved by upgrading JBossMessaging 1.4.0sp3 to 1.4.4ga in both(!) client and ESB. (Kinda complicated, refer to doc/index.html inside messaging zip file. Do not try to upgrade remoting in ESB.) Cheers, Tom. PS: It did also occur on some Linux machines, not only Mac. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4241995#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...