Samuel just pointed me at the answer - the param is coming from the previous request. So when you submit the form (and it evalutates the rendered expression to check whether the button push is valid) the param isn't available (it's the next request). I would suggest pushing (e.g. in pages.xml, a @Factory) your param.mode variable into page scope when the page is loaded, then it will be there when you submit the page. Alternatively you can use a h:commandLink with a nested f:param to propagate the parameter. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4091730#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...