src/Normalizer/JsonApiDocumentTopLevelNormalizer.php |  6 +++++-
 tests/src/Functional/JsonApiFunctionalTest.php       |  9 +--------
 .../JsonApiDocumentTopLevelNormalizerTest.php        | 20 +++++++++++++++-----
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php b/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
index 22c7e6e..51d0b1a 100644
--- a/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
+++ b/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
@@ -143,7 +143,11 @@ class JsonApiDocumentTopLevelNormalizer extends NormalizerBase implements Denorm
         // meta values from the relationship, whose deltas match with $id_list.
         $canonical_ids = [];
         foreach ($id_list as $delta => $uuid) {
-          if (empty($map[$uuid])) {
+          if (!isset($map[$uuid])) {
+            // @see \Drupal\jsonapi\Normalizer\EntityReferenceFieldNormalizer::normalize()
+            if ($uuid === 'virtual') {
+              continue;
+            }
             throw new NotFoundHttpException(sprintf('The resource identified by `%s:%s` (given as a relationship item) could not be found.', $relationship['data'][$delta]['type'], $uuid));
           }
           $reference_item = [
diff --git a/tests/src/Functional/JsonApiFunctionalTest.php b/tests/src/Functional/JsonApiFunctionalTest.php
index 4af293b..e25e4a0 100644
--- a/tests/src/Functional/JsonApiFunctionalTest.php
+++ b/tests/src/Functional/JsonApiFunctionalTest.php
@@ -530,12 +530,6 @@ class JsonApiFunctionalTest extends JsonApiFunctionalTestBase {
           ],
         ],
         'relationships' => [
-          'type' => [
-            'data' => [
-              'type' => 'node_type--node_type',
-              'id' => 'article',
-            ],
-          ],
           'field_tags' => [
             'data' => [
               [
@@ -618,8 +612,7 @@ class JsonApiFunctionalTest extends JsonApiFunctionalTestBase {
       'headers' => ['Content-Type' => 'application/vnd.api+json'],
     ]);
     $created_response = Json::decode($response->getBody()->__toString());
-    $this->assertEquals(201, $response->getStatusCode());
-    $this->assertEquals(0, count($created_response['data']['relationships']['field_tags']['data']));
+    $this->assertEquals(404, $response->getStatusCode());
     // 6. Decoding error.
     $response = $this->request('POST', $collection_url, [
       'body' => '{"bad json",,,}',
diff --git a/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php b/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
index a7da7b7..ff368a3 100644
--- a/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
+++ b/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
@@ -24,6 +24,7 @@ use Prophecy\Argument;
 use Symfony\Component\HttpFoundation\ParameterBag;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 /**
  * @coversDefaultClass \Drupal\jsonapi\Normalizer\JsonApiDocumentTopLevelNormalizer
@@ -499,6 +500,7 @@ class JsonApiDocumentTopLevelNormalizerTest extends JsonapiKernelTestBase {
           [$this->term1->id()],
           $this->user2->id(),
         ],
+        'taxonomy_term--tags:invalid-uuid',
       ],
       // Bad data in user and first tag.
       [
@@ -510,6 +512,7 @@ class JsonApiDocumentTopLevelNormalizerTest extends JsonapiKernelTestBase {
           [$this->term1->id()],
           NULL,
         ],
+        'user--user:also-invalid-uuid',
       ],
     ];
 
@@ -519,11 +522,18 @@ class JsonApiDocumentTopLevelNormalizerTest extends JsonapiKernelTestBase {
 
       list($request, $resource_type) = $this->generateProphecies('node', 'article');
       $this->container->get('request_stack')->push($request);
-      $node = $this
-        ->getNormalizer()
-        ->denormalize(Json::decode($payload), NULL, 'api_json', [
-          'resource_type' => $resource_type,
-        ]);
+      try {
+        $node = $this
+          ->getNormalizer()
+          ->denormalize(Json::decode($payload), NULL, 'api_json', [
+            'resource_type' => $resource_type,
+          ]);
+      }
+      catch (NotFoundHttpException $e) {
+        $non_existing_resource_identifier = $configuration[2];
+        $this->assertEquals("The resource identified by `$non_existing_resource_identifier` (given as a relationship item) could not be found.", $e->getMessage());
+        continue;
+      }
 
       /* @var \Drupal\node\Entity\Node $node */
       $this->assertInstanceOf('\Drupal\node\Entity\Node', $node);