Ticket #15903: 15903.diff

wp-includes/load.php

@@ -612 +612 @@
 function is_network_admin() {
         if ( defined('DOING_AJAX') && function_exists('get_current_screen') ) {
                 $screen = get_current_screen();
-                return (bool) $screen->is_network;
+                if ( isset( $screen->is_network ) )
+                        return (bool) $screen->is_network;
+                return false;
         }
 
         if ( defined( 'WP_NETWORK_ADMIN' ) )