I don't pretend to understand all the reasons why such an exception may be thrown. However if two threads are trying to signal a transition on the same process instance and one fails then I would say you do want to know about that. Furthermore presumably if a user interface is involved then you would want to give the user some visual indication of why the app now looks to be in a state that is inconsistent with what they expected. UI or not surely if there is a failure you want to rollback and not keep the app in an inconsistent state? Just gobbling up the exception and not throwing a new exception just seems plain wrong. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4164835#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...