diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 0309dc2..0d5bf44 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -407,8 +407,7 @@
     else {
       ajax.options.url += '&';
     }
-    // @todo Passing both always is kinda redicilous!
-    ajax.options.url += Drupal.ajax.AJAX_FORM_REQUEST + '=1&' + Drupal.ajax.WRAPPER_FORMAT + '=drupal_' + (element_settings.dialogType || 'ajax');
+    ajax.options.url += Drupal.ajax.WRAPPER_FORMAT + '=drupal_' + (element_settings.dialogType || 'ajax');
 
     // Bind the ajaxSubmit function to the element event.
     $(ajax.element).on(element_settings.event, function (event) {
@@ -433,11 +432,6 @@
   };
 
   /**
-   * Request key for a form that was triggered via AJAX.
-   */
-   Drupal.ajax.AJAX_FORM_REQUEST = 'ajax_form';
-
-  /**
    * URL query attribute to indicate the wrapper used to render a request.
    *
    * The wrapper format determines how the HTML is wrapped, for example in a
diff --git a/core/modules/file/src/Element/ManagedFile.php b/core/modules/file/src/Element/ManagedFile.php
index 3da9e42..5838e6c 100644
--- a/core/modules/file/src/Element/ManagedFile.php
+++ b/core/modules/file/src/Element/ManagedFile.php
@@ -130,9 +130,10 @@ public static function valueCallback(&$element, $input, FormStateInterface $form
   /**
    * #ajax callback for managed_file upload forms.
    *
-   * This ajax callback takes care about ensuring that there is no broken
-   * request due to too big files, as well as adding a class to the response
-   * that a new file got uploaded.
+   * This ajax callback takes care of the following things:
+   *   - Ensures that broken requests due to too big files are caught.
+   *   - Adds a class to the response to be able to highlight in the UI, that
+   *     a new file got uploaded.
    *
    * @param array $form
    *   The build form.
@@ -149,21 +150,10 @@ public static function uploadAjaxCallback(&$form, FormStateInterface &$form_stat
     $renderer = \Drupal::service('renderer');
 
     $form_parents = explode('/', $request->query->get('element_parents'));
-    $form_build_id = $request->query->get('form_build_id');
-    $request_form_build_id = $request->request->get('form_build_id');
-
-    if (empty($request_form_build_id) || $form_build_id !== $request_form_build_id) {
-      // Invalid request.
-      drupal_set_message(t('An unrecoverable error occurred. The uploaded file likely exceeded the maximum file size (@size) that this server supports.', array('@size' => format_size(file_upload_max_size()))), 'error');
-      $response = new AjaxResponse();
-      $status_messages = array('#type' => 'status_messages');
-      return $response->addCommand(new ReplaceCommand(NULL, $renderer->renderRoot($status_messages)));
-    }
 
     // Retrieve the element to be rendered.
     $form = NestedArray::getValue($form, $form_parents);
 
-
     // Add the special Ajax class if a new file was added.
     $current_file_count = $form_state->get('file_upload_delta_initial');
     if (isset($form['#file_upload_delta']) && $current_file_count < $form['#file_upload_delta']) {
@@ -210,7 +200,6 @@ public static function processManagedFile(&$element, FormStateInterface $form_st
       'options' => [
         'query' => [
           'element_parents' => implode('/', $element['#array_parents']),
-          'form_build_id' => $complete_form['form_build_id']['#value'],
         ],
       ],
       'wrapper' => $element['#id'] . '-ajax-wrapper',
diff --git a/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php b/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
index 08ea7b3..05ce286 100644
--- a/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
+++ b/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
@@ -410,7 +410,6 @@ public static function process($element, FormStateInterface $form_state, $form)
       $new_options = array(
         'query' => array(
           'element_parents' => implode('/', $parents),
-          'form_build_id' => $form['form_build_id']['#value'],
         ),
       );
       $field_element = NestedArray::getValue($form, $parents);