It does not only look like a bug, it is a bug. For page parameters, one can specify a JSF converter and a JSF validator. [SeamReference -> 5.1.1.1.3. Conversion and Validation] A JSF validator can be specified by way of a JSF validator id or alternatively a value expression. If a value expression is used, it should refer to an object which implements interface javax.faces.validator.Validator, and thus the method javax.faces.validator.Validator.validate(FacesContext context, UIComponent component, Object value) throws ValidatorException With the current code in org.jboss.seam.navigation.Pages.convertAndValidateStringValuesInPageContext(), the problem is that Validator.validate() is called not with the converted object value, but rather with the unconverted (!) String value for the page parameter. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4109646#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...