diff --git a/core/lib/Drupal/Core/Render/Element/MachineName.php b/core/lib/Drupal/Core/Render/Element/MachineName.php
index 6e3ccb6b32..9aa053efe4 100644
--- a/core/lib/Drupal/Core/Render/Element/MachineName.php
+++ b/core/lib/Drupal/Core/Render/Element/MachineName.php
@@ -150,6 +150,17 @@ public static function processMachineName(&$element, FormStateInterface $form_st
       'field_suffix' => $element['#field_suffix'],
     ];
 
+    // Store the initial value in form state. The machine name needs this to
+    // ensure that the exists function is not called for existing values when
+    // editing them.
+    $initial_values = $form_state->get('machine_name.initial_values') ?: [];
+    // Store the initial values in an array so we can differentiate between a
+    // NULL default value and a new machine name element.
+    if (!array_key_exists($element['#id'], $initial_values)) {
+      $initial_values[$element['#id']] = $element['#default_value'];
+      $form_state->set('machine_name.initial_values', $initial_values);
+    }
+
     // By default, machine names are restricted to Latin alphanumeric characters.
     // So, default to LTR directionality.
     if (!isset($element['#attributes'])) {
@@ -246,15 +257,13 @@ public static function validateMachineName(&$element, FormStateInterface $form_s
       }
     }
 
-    // Verify that the machine name is unique. Check form state if we need to
-    // explicitly validate the element. This happens every time when an error
-    // has been set, since this breaks on AJAX requests
-    $needs_revalidating = $form_state->get('machine_name.needs_revalidating') ?: [];
-    if ($element['#default_value'] !== $element['#value'] || isset($needs_revalidating[$element['#name']])) {
+    // Verify that the machine name is unique. If the value matches the initial
+    // default value then it does not need to be validated as the machine name
+    // elements assumes the form is editing the existing value.
+    $initial_values = $form_state->get('machine_name.initial_values') ?: [];
+    if (!array_key_exists($element['#id'], $initial_values) || $initial_values[$element['#id']] !== $element['#value']) {
       $function = $element['#machine_name']['exists'];
       if (call_user_func($function, $element['#value'], $element, $form_state)) {
-        $needs_revalidating[$element['#name']] = TRUE;
-        $form_state->set('machine_name.needs_revalidating', $needs_revalidating);
         $form_state->setError($element, t('The machine-readable name is already in use. It must be unique.'));
       }
     }