diff --git a/core/modules/system/src/Tests/Update/UpdatePathRC1TestBaseTest.php b/core/modules/system/src/Tests/Update/UpdatePathRC1TestBaseTest.php
index 900565d..54c2d1e 100644
--- a/core/modules/system/src/Tests/Update/UpdatePathRC1TestBaseTest.php
+++ b/core/modules/system/src/Tests/Update/UpdatePathRC1TestBaseTest.php
@@ -65,6 +65,8 @@ public function testDatabaseLoaded() {
     $this->assertText('Site-Install');
     $extensions = \Drupal::service('config.storage')->read('core.extension');
     $this->assertTrue(isset($extensions['theme']['stable']), 'Stable is installed after updating.');
+    $blocks = \Drupal::entityManager()->getStorage('block')->loadByProperties(['theme' => 'stable']);
+    $this->assertTrue(empty($blocks), 'No blocks have been placed for Stable.');
   }
 
 }