diff --git a/core/modules/file/lib/Drupal/file/Plugin/field/widget/FileWidget.php b/core/modules/file/lib/Drupal/file/Plugin/field/widget/FileWidget.php
index 98a7a961337104dfbc89c8e0d1b323fc7bb48dfb..7928947e75d78bf097102d52d0553e3b3e12dcdf 100644
--- a/core/modules/file/lib/Drupal/file/Plugin/field/widget/FileWidget.php
+++ b/core/modules/file/lib/Drupal/file/Plugin/field/widget/FileWidget.php
@@ -141,6 +141,7 @@ protected function formMultipleElements(EntityInterface $entity, array $items, $
       // The group of elements all-together need some extra functionality after
       // building up the full list (like draggable table rows).
       $elements['#file_upload_delta'] = $delta;
+      $elements['#type'] = 'details';
       $elements['#theme'] = 'file_widget_multiple';
       $elements['#theme_wrappers'] = array('details');
       $elements['#process'] = array('file_field_widget_process_multiple');