The serialization of the NestedJarFromStream is incorrect. Its using default serialization of these fields: private transient ZipInputStream zis; private URL jarURL; private URL entryURL; private long lastModified; private long size; private AtomicBoolean inited = new AtomicBoolean(false); The problem is that the inited flag should not be serialized as this implies its parents fields: private transient List entries; private transient Map<String, VirtualFileHandler> entryMap; have been initialized. They will not be after deserialization of NestedJarFromStream as it lazily does initialization. We need to be careful when adding fields to a class that is using the default java serialization contract. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4133376#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...