"pfrontiero" wrote : The only way we have been able to get around this problem is to disable the WarClassLoaderDeployer (by commenting it out in war-deployers-jboss-beans.xml), however, this is not an ideal workaround. If you application depends on using the version of xerces included in your war, this approach will not work as it essentially forces your app to use the xerces bundled with JBoss. If you're going to use this approach, you may as well just remove the xercesImpl.jar from your war. This way you will at least keep the war classloader isolation for yours, and other apps on the server. The other way to achieve the same result as with your approach is to use jboss-classloading.xml and set parent-first=true as specified in the linked post above. But again, this will change the standard servlet spec classloading semantics and will still not allow you to use your xerces version. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4250224#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...