.../src/Entity/MenuLinkContent.php                 |  5 +++-
 .../src/Form/MenuLinkContentForm.php               | 28 ----------------------
 core/modules/menu_ui/src/MenuForm.php              |  2 +-
 3 files changed, 5 insertions(+), 30 deletions(-)

diff --git a/core/modules/menu_link_content/src/Entity/MenuLinkContent.php b/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
index 420ebca..b67db69 100644
--- a/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
+++ b/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
@@ -149,7 +149,10 @@ protected function getPluginDefinition() {
     $definition['menu_name'] = $this->getMenuName();
 
     if ($url_object = $this->getUrlObject()) {
-      if ($url_object->isExternal()) {
+      $definition['url'] = NULL;
+      $definition['route_name'] = NULL;
+      $definition['route_parameters'] = [];
+      if (!$url_object->isRouted()) {
         $definition['url'] = $url_object->getUri();
       }
       else {
diff --git a/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php b/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php
index d4180ed..a0e9a28 100644
--- a/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php
+++ b/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php
@@ -244,15 +244,6 @@ protected function actions(array $form, FormStateInterface $form_state) {
   /**
    * {@inheritdoc}
    */
-  public function validate(array $form, FormStateInterface $form_state) {
-    $this->doValidate($form, $form_state);
-
-    parent::validate($form, $form_state);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
   public function buildEntity(array $form, FormStateInterface $form_state) {
     /** @var \Drupal\menu_link_content\MenuLinkContentInterface $entity */
     $entity = parent::buildEntity($form, $form_state);
@@ -287,23 +278,4 @@ public function save(array $form, FormStateInterface $form_state) {
     }
   }
 
-  /**
-   * Validates the form, both on the menu link edit and content menu link form.
-   *
-   * $form is not currently used, but passed here to match the normal form
-   * validation method signature.
-   *
-   * @param array $form
-   *   A nested array form elements comprising the form.
-   * @param \Drupal\Core\Form\FormStateInterface $form_state
-   *   The current state of the form.
-   */
-  protected function doValidate(array $form, FormStateInterface $form_state) {
-    $extracted = $this->pathValidator->getUrlIfValid($form_state->getValue(['link', 0, 'uri']));
-
-    if (!$extracted) {
-      $form_state->setErrorByName('link][0][uri', $this->t("The path '@link_path' is either invalid or you do not have access to it.", array('@link_path' => $form_state->getValue(['link', 0, 'uri']))));
-    }
-  }
-
 }
diff --git a/core/modules/menu_ui/src/MenuForm.php b/core/modules/menu_ui/src/MenuForm.php
index b5aef7b..987858e 100644
--- a/core/modules/menu_ui/src/MenuForm.php
+++ b/core/modules/menu_ui/src/MenuForm.php
@@ -346,7 +346,7 @@ protected function buildOverviewTreeForm($tree, $delta) {
         if (!$link->isEnabled()) {
           $form[$id]['title']['#markup'] .= ' (' . $this->t('disabled') . ')';
         }
-        elseif (($url = $link->getUrlObject()) && !$url->isExternal() && $url->getRouteName() == 'user.page') {
+        elseif (($url = $link->getUrlObject()) && $url->isRouted() && $url->getRouteName() == 'user.page') {
           $form[$id]['title']['#markup'] .= ' (' . $this->t('logged in users only') . ')';
         }