We have an application which runs on most of app servers. We have all jars packaged and loaded using custom class loaders. serializer.jar is loaded by Jboss ''org.apache.xalan" and also loaded by our custom class loader. We are getting following class cast exception due to this. i have added "org.apache.xalan" module into <exclusions> in jboss-deploment-structure.xml but still same exception. is there a way to exclude this module loading. your help is greatly appreciated.