diff --git a/core/modules/serialization/serialization.services.yml b/core/modules/serialization/serialization.services.yml
index dca6094..eb2690a 100644
--- a/core/modules/serialization/serialization.services.yml
+++ b/core/modules/serialization/serialization.services.yml
@@ -33,7 +33,7 @@ services:
       # this modules generic field item normalizer.
       # @todo Find a better way for this in https://www.drupal.org/node/2575761.
       - { name: normalizer, priority: 8 }
-    arguments: ['@entity.repository']
+    arguments: ['@entity.repository', '@router.route_provider']
   serialization.normalizer.field_item:
     class: Drupal\serialization\Normalizer\FieldItemNormalizer
     tags:
diff --git a/core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php b/core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php
index ea2e020..80c7bdb 100644
--- a/core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php
+++ b/core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php
@@ -3,6 +3,7 @@
 namespace Drupal\serialization\Normalizer;
 
 use Drupal\Core\Entity\EntityRepositoryInterface;
+use Drupal\Core\Routing\RouteProvider;
 use Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem;
 use Symfony\Component\Serializer\Exception\InvalidArgumentException;
 use Symfony\Component\Serializer\Exception\UnexpectedValueException;
@@ -27,13 +28,23 @@ class EntityReferenceFieldItemNormalizer extends FieldItemNormalizer {
   protected $entityRepository;
 
   /**
+   * The route provider.
+   *
+   * @var \Drupal\Core\Routing\RouteProvider
+   */
+  protected $routeProvider;
+
+  /**
    * Constructs a EntityReferenceFieldItemNormalizer object.
    *
    * @param \Drupal\Core\Entity\EntityRepositoryInterface $entity_repository
    *   The entity repository.
+   * @param \Drupal\Core\Routing\RouteProvider $route_provider
+   *   The route provider.
    */
-  public function __construct(EntityRepositoryInterface $entity_repository) {
+  public function __construct(EntityRepositoryInterface $entity_repository, RouteProvider $route_provider) {
     $this->entityRepository = $entity_repository;
+    $this->routeProvider = $route_provider;
   }
 
   /**
@@ -51,7 +62,13 @@ public function normalize($field_item, $format = NULL, array $context = []) {
       // Add a 'url' value if there is a reference and a canonical URL. Hard
       // code 'canonical' here as config entities override the default $rel
       // parameter value to 'edit-form.
-      if ($url = $entity->url('canonical')) {
+      // Since some entity types don't have a canonical URL, we check the
+      // route provider to ensure that it does before we try generating a
+      // canonical URL.
+      if (
+        $this->routeProvider->getRouteByName('entity.' . $values['target_type'] . '.canonical') &&
+        $url = $entity->url('canonical')
+      ) {
         $values['url'] = $url;
       }
     }