Ticket #21573: 21573.2.diff

src/wp-includes/ms-functions.php

@@ -1612 +1612 @@
  * @since MU
  */
 function maybe_redirect_404() {
-        if ( is_main_site() && is_404() && defined( 'NOBLOGREDIRECT' ) && ( $destination = apply_filters( 'blog_redirect_404', NOBLOGREDIRECT ) ) ) {
+        if ( ! is_subdomain_install() && is_main_site() && is_404() && defined( 'NOBLOGREDIRECT' ) && ( $destination = apply_filters( 'blog_redirect_404', NOBLOGREDIRECT ) ) ) {
                 if ( $destination == '%siteurl%' )
                         $destination = network_home_url();
                 wp_redirect( $destination );