I suspect you have another copy of JBoss Cache deployed with your app. The CCE is occuring at line 416 of FileCacheLoader which does this: nd = (NodeData) in.readObject(); Just tested, and when a CCE happens, the message of the CCE is the type of the object being cast, not the target type. The message your stack trace is showing is java.lang.ClassCastException: org.jboss.cache.loader.NodeData The message says the object being cast is of type NodeData, i.e. seemingly what the cast expects. That suggests to me that the NodeData class has been loaded by two different classloaders; load a class with the same name from 2 different classloaders and try to cast and you'll get a CCE. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150410#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...