diff --git a/core/lib/Drupal/Core/Render/Element/RenderElement.php b/core/lib/Drupal/Core/Render/Element/RenderElement.php
index 627b041e04..5e1cc95e74 100644
--- a/core/lib/Drupal/Core/Render/Element/RenderElement.php
+++ b/core/lib/Drupal/Core/Render/Element/RenderElement.php
@@ -244,6 +244,7 @@ public static function processAjaxForm(&$element, FormStateInterface $form_state
    *   - #ajax['event']
    *   - #ajax['prevent']
    *   - #ajax['url']
+   *   - #ajax['type']
    *   - #ajax['callback']
    *   - #ajax['options']
    *   - #ajax['wrapper']
@@ -340,6 +341,7 @@ public static function preRenderAjaxForm($element) {
       // to be substantially different for a JavaScript triggered submission.
       $settings += [
         'url' => NULL,
+        'type' => 'POST',
         'options' => ['query' => []],
         'dialogType' => 'ajax',
       ];