core/modules/system/src/SystemConfigSubscriber.php | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/core/modules/system/src/SystemConfigSubscriber.php b/core/modules/system/src/SystemConfigSubscriber.php
index 3c0de5f..d08c961 100644
--- a/core/modules/system/src/SystemConfigSubscriber.php
+++ b/core/modules/system/src/SystemConfigSubscriber.php
@@ -5,6 +5,7 @@
 use Drupal\Core\Config\ConfigCrudEvent;
 use Drupal\Core\Config\ConfigEvents;
 use Drupal\Core\Config\ConfigImporterEvent;
+use Drupal\Core\PhpStorage\PhpStorageFactory;
 use Drupal\Core\Routing\RouteBuilderInterface;
 use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
@@ -41,6 +42,10 @@ public function onConfigSave(ConfigCrudEvent $event) {
     $saved_config = $event->getConfig();
     if ($saved_config->getName() == 'system.theme' && ($event->isChanged('admin') || $event->isChanged('default'))) {
       $this->routerBuilder->setRebuildNeeded();
+      // Wipe the Twig PHP Storage cache, to ensure templates that extend or
+      // include another template use the correct list of candidate templates.
+      // @see \Drupal\Core\Template\ThemeRegistryNodeVisitor
+      PhpStorageFactory::get('twig')->deleteAll();
     }
   }