diff --git a/core/modules/file/src/Element/ManagedFile.php b/core/modules/file/src/Element/ManagedFile.php
index 426f40c..1b04837 100644
--- a/core/modules/file/src/Element/ManagedFile.php
+++ b/core/modules/file/src/Element/ManagedFile.php
@@ -341,7 +341,7 @@ public static function processManagedFile(&$element, FormStateInterface $form_st
     // Add the extension list to the page as JavaScript settings.
     if (isset($element['#upload_validators']['file_validate_extensions'][0])) {
       $extension_list = implode(',', array_filter(explode(' ', $element['#upload_validators']['file_validate_extensions'][0])));
-      $element['upload']['#attached']['drupalSettings']['file']['elements']['#' . $element['#id']] = $extension_list;
+      $element['upload']['#attached']['drupalSettings']['file']['elements']['#' . $element['#id'] . '-upload'] = $extension_list;
     }
 
     // Let #id point to the file element, so the field label's 'for' corresponds