This has to do the way JBossRemoting is solving classLoader operations. I believe JBossRemoting is aways doing loader.loadClass, and on JVM 1.6 it's supposed to aways do a Class.forName(..,...,classLoader). So.. it is some inconsistent change documented on compatibility issues on the JVM 1.6. We will have to change some code to work on JVM 1.6. As for the serialization type... on UnifiedInvoker you can add the parameter type to serialization parameter type="serialization" value="jboss" Take a look on Remoting documentation for the exact parameter name (I have such a bad memory :-)... and look for your UnifiedInvoker configuration. For EJB3 I believe is under ejb3.deployer directory. (If it wasn't changed recenlty) If you can't find I can do a quick research for you. Let me know on that case. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3964984#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...