I have the same problem, using Rational Software Architect 7 - WAS 6.1 runtime. I think is a problem with the IBM -JSF implementation, I was doing some decompile over com.ibm.ws.webcontainer_2.0.0.jar , but can't found the issue, is something related with this code : obj = (ApplicationFactory)FactoryFinder.getFactory("javax.faces.application.ApplicationFactory"); application = (ApplicationImpl)((ApplicationFactory) (obj)).getApplication(); The second line give the cast exception, I think they (IBM) have to cast to (Application) not to (ApplicationImpl) because org.jboss.seam.jsf.SeamApplication11 extend for application. But to try to find a workaround for this I need more time and help from the JBoss Seam. I really hope that someone or me can find a workaround or make a patch, so people out there can use Seam on WAS 6.1 with the IBM JSF implementation. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4048022#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...