Hi, This has to do with the new marshaller in 1.4.0 not recognising an object that has been serialised as a part of an RPC call and not being able to unmarshal it. Could you post some more logs - say the last 20 lines or so before this happened? Also, could you describe what was going on at the time, if you can accurately recreate it? Cheers, Manik View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3959672#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...