core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php | 1 +
 1 file changed, 1 insertion(+)

diff --git a/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php b/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
index b05c05d39c..e53ebaee45 100644
--- a/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
+++ b/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
@@ -374,6 +374,7 @@ protected function initConfig(ContainerInterface $container) {
     }
     $config->getEditable('system.theme')
       ->set('default', $this->theme)
+      ->set('admin', 'seven')
       ->save();
   }