More information: This behavior is not repeated each time. In most cases occurs in Internet Explorer and some in Firefox. Seam FAQ wrote: http://wiki.jboss.org/wiki/Wiki.jsp?page=SeamProblemsFAQ "I've configured Seam's exception handling, but it doesn't always work If the exception is thrown early enough in the page rendering process, Seam is able to handle the exception, however, it doesn't work when the page is rendered partially. This occurs because once the response has started to be written, you can't then do a redirect. " I'm use RichFaces (but no use ajax) and trinidad:datatable (no ajax too). These libraries may be causing this problem? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4120406#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...