Issue #2914785 by acbramley, jungle, Hardik_Patel_12, mrinalini9, larowlan:...

Issue #2914785 by acbramley, jungle, Hardik_Patel_12, mrinalini9, larowlan: Entities with external urls as a uri relationship can not be deleted when menu_link_content is installed

core/modules/menu_link_content/menu_link_content.module

@@ -104,6 +104,11 @@ function menu_link_content_entity_predelete(EntityInterface $entity) {
   $entity_type_id = $entity->getEntityTypeId();
   foreach ($entity->uriRelationships() as $rel) {
     $url = $entity->toUrl($rel);
+    // Entities can provide uri relationships that are not routed, in this case
+    // getRouteParameters() will throw an exception.
+    if (!$url->isRouted()) {
+      continue;
+    }
     $route_parameters = $url->getRouteParameters();
     if (!isset($route_parameters[$entity_type_id])) {
       // Do not delete links which do not relate to this exact entity. For

core/modules/menu_link_content/tests/src/Kernel/MenuLinksTest.php

@@ -4,6 +4,7 @@
 
 use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Core\Menu\MenuTreeParameters;
+use Drupal\entity_test\Entity\EntityTestExternal;
 use Drupal\KernelTests\KernelTestBase;
 use Drupal\menu_link_content\Entity\MenuLinkContent;
 use Drupal\system\Entity\Menu;
@@ -17,11 +18,10 @@
 class MenuLinksTest extends KernelTestBase {
 
   /**
-   * Modules to enable.
-   *
-   * @var array
+   * {@inheritdoc}
    */
-  public static $modules = [
+  protected static $modules = [
+    'entity_test',
     'link',
     'menu_link_content',
     'router_test',
@@ -46,6 +46,7 @@ protected function setUp() {
 
     $this->installSchema('system', ['sequences']);
     $this->installSchema('user', ['users_data']);
+    $this->installEntitySchema('entity_test_external');
     $this->installEntitySchema('menu_link_content');
     $this->installEntitySchema('user');
 
@@ -163,6 +164,12 @@ public function testMenuLinkOnEntityDelete() {
     $user = User::create(['name' => 'username']);
     $user->save();
 
+    // Create External test entity.
+    $external_entity = EntityTestExternal::create();
+    $external_entity->save();
+    // Ensure an external entity can be deleted.
+    $external_entity->delete();
+
     // Create "canonical" menu link pointing to the user.
     $menu_link_content = MenuLinkContent::create([
       'title' => 'username profile',

core/modules/system/tests/modules/entity_test/src/Entity/EntityTestExternal.php

+<?php
+
+namespace Drupal\entity_test\Entity;
+
+use Drupal\Core\Url;
+
+/**
+ * Test entity class.
+ *
+ * @ContentEntityType(
+ *   id = "entity_test_external",
+ *   label = @Translation("Entity test external"),
+ *   base_table = "entity_test_external",
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "uuid" = "uuid",
+ *     "bundle" = "type",
+ *   },
+ *   links = {
+ *     "canonical" = "/entity_test_external/{entity_test_external}"
+ *   },
+ * )
+ */
+class EntityTestExternal extends EntityTest {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function toUrl($rel = 'canonical', array $options = []) {
+    if ($rel === 'canonical') {
+      return Url::fromUri('http://example.com', $options);
+    }
+    return parent::toUrl($rel, $options);
+  }
+
+}