Ticket #38271: 38271.diff

src/wp-admin/js/post.js

@@ -506 +506 @@
                         active_post_lock: $('#active_post_lock').val()
                 };
 
+                if ( typeof data.active_post_lock === 'undefined' ) {
+                        return;
+                }
+
                 if (window.FormData && window.navigator.sendBeacon) {
                         var formData = new window.FormData();