if http://localhost:8080/lutece/jsp/admin/plugins/form/ModifyForm.jsp?id_form=1 and you are not authentified => error 500 because of AuthenticationFilter.java:176 I though this exception would be catch by the errorPage tag in the ModifyForm.jsp but it isn't. Because the filter is crashing and not the jsp. Note : this should be cath by the web.xml error declaration.