Sorry to get back to you late. I have finally got a chance to try to reproduce your problem. I am using the latest jboss-4.0 src (of which should be very close to 4.0.5.GA). But I can't reproduce your problem. I have the current cluster counter test running and then have a new node startup to join. No exception occurred. However, I don't see the round robin going to the new node either. I will look into this part more. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3983343#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...