diff -u b/core/lib/Drupal/Core/Theme/ThemeManager.php b/core/lib/Drupal/Core/Theme/ThemeManager.php
--- b/core/lib/Drupal/Core/Theme/ThemeManager.php
+++ b/core/lib/Drupal/Core/Theme/ThemeManager.php
@@ -158,7 +158,7 @@
     $original_hook = $hook;
 
     // If there's no implementation, check for more generic fallbacks.
-    // If there's still no implementation, log an error and return an empty
+    // If there's still no implementation, trigger an error and return an empty
     // string.
     if (!$theme_registry->has($hook)) {
       // Iteratively strip everything after the last '__' delimiter, until an
only in patch2:
unchanged:
--- a/core/modules/field/src/Tests/Boolean/BooleanFormatterTest.php
+++ b/core/modules/field/src/Tests/Boolean/BooleanFormatterTest.php
@@ -27,7 +27,7 @@ class BooleanFormatterTest extends KernelTestBase {
    *
    * @var array
    */
-  public static $modules = ['field', 'text', 'entity_test', 'user'];
+  public static $modules = ['field', 'text', 'entity_test', 'user', 'system'];
 
   /**
    * @var string