strange behaviour of template_redirect in IE8 October 6, 2022 by Tarik Billa I am updated the answer, so that it will be helpfull to others as well. (For IE, IIRC it's 512 bytes) Helpful links: https://stackoverflow.com/questions/11121286/404-page-not-showing-up-in-ie9#answer-11133855 https://stackoverflow.com/questions/3970093/include-after-php-404-header-returning-oops-this-link-appears-to-be-broken