Ticket #21745: 21745.diff

wp-admin/admin.php

@@ -41 +41 @@
         do_action('after_db_upgrade');
 } elseif ( get_option('db_version') != $wp_db_version && empty($_POST) ) {
         if ( !is_multisite() ) {
+                nocache_headers();
                 wp_redirect(admin_url('upgrade.php?_wp_http_referer=' . urlencode(stripslashes($_SERVER['REQUEST_URI']))));
                 exit;
         } elseif ( apply_filters( 'do_mu_upgrade', true ) ) {

wp-admin/upgrade.php

@@ -17 +17 @@
 /** Load WordPress Bootstrap */
 require( '../wp-load.php' );
 
+nocache_headers();
+
 timer_start();
 require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );