diff --git a/src/Routing/Routes.php b/src/Routing/Routes.php
index 764a35b..eeba4f0 100644
--- a/src/Routing/Routes.php
+++ b/src/Routing/Routes.php
@@ -232,19 +232,6 @@ class Routes implements ContainerInjectionInterface {
     }
 
     foreach ($resource_type->getRelatableResourceTypes() as $relationship_field_name => $target_resource_types) {
-      // Do not create routes for relationships that only target internal
-      // resource types.
-      if (!static::hasNonInternalTargetResourceTypes($target_resource_types)) {
-        continue;
-      }
-
-      // Get an individual resource's related resources.
-      $related_route = new Route("/{$path}/{{$entity_type_id}}/{$relationship_field_name}");
-      $related_route->setMethods(['GET']);
-      $related_route->addDefaults(['related' => $relationship_field_name]);
-      $related_route->setRequirement(RelationshipFieldAccess::ROUTE_REQUIREMENT_KEY, $relationship_field_name);
-      $routes->add(static::getRouteName($resource_type, "$relationship_field_name.related"), $related_route);
-
       // Read, update, add, or remove an individual resources relationships to
       // other resources.
       $relationship_route = new Route("/{$path}/{{$entity_type_id}}/relationships/{$relationship_field_name}");
@@ -259,6 +246,17 @@ class Routes implements ContainerInjectionInterface {
       $relationship_route->setRequirement(RelationshipFieldAccess::ROUTE_REQUIREMENT_KEY, $relationship_field_name);
       $relationship_route->setRequirement('_csrf_request_header_token', 'TRUE');
       $routes->add(static::getRouteName($resource_type, "$relationship_field_name.relationship"), $relationship_route);
+
+      // Only create routes for related routes that target at least one
+      // non-internal resource type.
+      if (static::hasNonInternalTargetResourceTypes($target_resource_types)) {
+        // Get an individual resource's related resources.
+        $related_route = new Route("/{$path}/{{$entity_type_id}}/{$relationship_field_name}");
+        $related_route->setMethods(['GET']);
+        $related_route->addDefaults(['related' => $relationship_field_name]);
+        $related_route->setRequirement(RelationshipFieldAccess::ROUTE_REQUIREMENT_KEY, $relationship_field_name);
+        $routes->add(static::getRouteName($resource_type, "$relationship_field_name.related"), $related_route);
+      }
     }
 
     // Add entity parameter conversion to every route.
diff --git a/tests/src/Functional/JsonApiFunctionalTest.php b/tests/src/Functional/JsonApiFunctionalTest.php
index 35a8566..d7f6bee 100644
--- a/tests/src/Functional/JsonApiFunctionalTest.php
+++ b/tests/src/Functional/JsonApiFunctionalTest.php
@@ -772,7 +772,7 @@ class JsonApiFunctionalTest extends JsonApiFunctionalTestBase {
       'body' => Json::encode($body),
       'headers' => ['Content-Type' => 'application/vnd.api+json'],
     ]);
-    $this->assertEquals(403, $response->getStatusCode());
+    $this->assertEquals(401, $response->getStatusCode());
     $response = $this->request('DELETE', $relationship_url, [
       // Remove the existing relationship item.
       'body' => Json::encode($body),
diff --git a/tests/src/Functional/JsonApiRegressionTest.php b/tests/src/Functional/JsonApiRegressionTest.php
index d8ad43b..61dfb20 100644
--- a/tests/src/Functional/JsonApiRegressionTest.php
+++ b/tests/src/Functional/JsonApiRegressionTest.php
@@ -5,6 +5,7 @@ namespace Drupal\Tests\jsonapi\Functional;
 use Drupal\comment\Entity\Comment;
 use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
 use Drupal\comment\Tests\CommentTestTrait;
+use Drupal\Component\Serialization\Json;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\Core\Url;
 use Drupal\node\Entity\Node;
@@ -71,8 +72,6 @@ class JsonApiRegressionTest extends JsonApiFunctionalTestBase {
     $this->addDefaultCommentField('node', 'article');
     $this->addDefaultCommentField('taxonomy_term', 'tags', 'comment', CommentItemInterface::OPEN, 'tcomment');
     $this->drupalCreateContentType(['type' => 'page']);
-    $this->rebuildAll();
-
     $this->createEntityReferenceField(
       'node',
       'page',
@@ -88,6 +87,7 @@ class JsonApiRegressionTest extends JsonApiFunctionalTestBase {
       ],
       FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED
     );
+    $this->rebuildAll();
 
     // Create data.
     $node = Node::create([
diff --git a/tests/src/Unit/Routing/RoutesTest.php b/tests/src/Unit/Routing/RoutesTest.php
index 726bd08..2b42603 100644
--- a/tests/src/Unit/Routing/RoutesTest.php
+++ b/tests/src/Unit/Routing/RoutesTest.php
@@ -71,10 +71,11 @@ class RoutesTest extends UnitTestCase {
     //   type.
     // - 2 related routes; GET for the non-internal resource type relationships
     //   fields: external & both.
-    // - 2 relationship routes; all HTTP methods handled by the one route for
-    //   the non-internal resource type.
+    // - 3 relationship routes; All HTTP methods handled by the same route.
+    //   `relationship` routes are generated even for internal target resource
+    //   types (`related` routes are not).
     // - 1 for the JSON API entry point.
-    $this->assertEquals(10, $routes->count());
+    $this->assertEquals(11, $routes->count());
 
     $iterator = $routes->getIterator();
     // Check the collection route.