I found the cause of the problem: I do not use cookies in my web application for session tracking (Tomcat is set to cookies="false"). Because of this, Seam looses the current session, and renders the error page in a new session. If I switch on cookies, the exception handling works also for the exception generated by MultipartFilter. I guess it should be quite a common situation to have a web application where using cookies is not allowed. (For example I am not allowed to use cookies.) Could the Seam exception handling be prepared for this situation, or is it a fundamental problem that cannot be easily solved? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4102882#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...