diff --git a/core/modules/file/src/Element/ManagedFile.php b/core/modules/file/src/Element/ManagedFile.php
index acb4825..82fe57a 100644
--- a/core/modules/file/src/Element/ManagedFile.php
+++ b/core/modules/file/src/Element/ManagedFile.php
@@ -296,7 +296,7 @@ public static function processManagedFile(&$element, FormStateInterface $form_st
 
       // Existing files only have a remove button, determine if it was clicked.
       $remove_clicked = FALSE;
-      if (!isset($handled_fields[$element['#field_name']])) {
+      if (isset($element['#field_name']) && !isset($handled_fields[$element['#field_name']])) {
         $input = $form_state->getUserInput();
         // Handle non ajax requests.
         $remove_clicked  = isset($input[$element['remove_button']['#name']]);