diff -u b/core/modules/file/src/Controller/FileWidgetAjaxController.php b/core/modules/file/src/Controller/FileWidgetAjaxController.php
--- b/core/modules/file/src/Controller/FileWidgetAjaxController.php
+++ b/core/modules/file/src/Controller/FileWidgetAjaxController.php
@@ -67,7 +67,7 @@
       'message' => t('Starting upload...'),
       'percentage' => -1,
     ];
-    if (isset($status[$current]) && !empty($status[$total])) {
+    if (isset($status[$current]) && !empty($status[$current]) && isset($status[$total]) && !empty($status[$total])) {
       $progress['message'] = t('Uploading... (@current of @total)', [
         '@current' => format_size($status[$current]),
         '@total' => format_size($status[$total]),