If you want to use sesssion replication, I don't think this is fixable, at least no fix that doesn't involve repackaging the JBC 3 classes as discussed at http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4200115#.... See my post above where I say anonymous wrote : if the 3.0.1 classes are in the war, they'll be visible to the session replication code as well, likely leading to incompatible type issue (e.g. which version or org.jboss.cache.Fqn). Your java.lang.VerifyError is the kind of thing I was talking about. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4200395#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...