It seems JBoss AS 4.2.3 have a faulty JSF implementation that causes some classloader problems. This is fixed in EAP 4.3 and JBoss 5. The suggested workaround for AS 4.2.3 from the seam team is to download the latest JSF implementation and replace it. JSF lives in server/default/deploy/jboss-web.deployer/jsf-libs/{jsf-api.jar, jsf-impl.jar}. Could you try that and let me know if that solves it for you ? View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4224448#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...