diff -u b/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
--- b/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -916,6 +916,7 @@
     // new session into the master request if one was present before.
     if (($request_stack = $this->container->get('request_stack', ContainerInterface::NULL_ON_INVALID_REFERENCE))) {
       if ($request = $request_stack->getMasterRequest()) {
+        $subrequest = TRUE;
         if ($request->hasSession()) {
           $request->setSession($this->container->get('session'));
         }
@@ -928,9 +929,10 @@
 
     \Drupal::setContainer($this->container);
-    // If there is a request stack, we want to make sure other parts of the
-    // codebase can react to this.
-    if ($request) {
-      $this->container->get('event_dispatcher')->dispatch(self::CONTAINER_INITIALIZE_FINISHED);
+
+    // Allow other parts of the codebase to react on container initialization in
+    // subrequest.
+    if (isset($subrequest) && $subrequest) {
+      $this->container->get('event_dispatcher')->dispatch(self::CONTAINER_INITIALIZE_SUBREQUEST_FINISHED);
     }
 
     // If needs dumping flag was set, dump the container.
diff -u b/core/lib/Drupal/Core/DrupalKernelInterface.php b/core/lib/Drupal/Core/DrupalKernelInterface.php
--- b/core/lib/Drupal/Core/DrupalKernelInterface.php
+++ b/core/lib/Drupal/Core/DrupalKernelInterface.php
@@ -15,14 +15,14 @@
 interface DrupalKernelInterface extends HttpKernelInterface, ContainerAwareInterface {
 
   /**
-   * Name of the event fired when the service container finished initializing.
+   * Event fired when the service container finished initializing in subrequest.
    *
    * This event allows you to initialize overrides such as language to the
    * services.
    *
    * @var string
    */
-  const CONTAINER_INITIALIZE_FINISHED = 'kernel.container.finish_container_initialize';
+  const CONTAINER_INITIALIZE_SUBREQUEST_FINISHED = 'kernel.container.finish_container_initialize_subrequest';
 
   /**
    * Boots the current kernel.
diff -u b/core/modules/language/src/EventSubscriber/LanguageRequestSubscriber.php b/core/modules/language/src/EventSubscriber/LanguageRequestSubscriber.php
--- b/core/modules/language/src/EventSubscriber/LanguageRequestSubscriber.php
+++ b/core/modules/language/src/EventSubscriber/LanguageRequestSubscriber.php
@@ -79,7 +79,7 @@
   /**
    * Initializes config overrides whenever the service container is rebuilt.
    */
-  public function onContainerInitializeFinished() {
+  public function onContainerInitializeSubrequestFinished() {
     $this->setLanguageOverrides();
   }
 
@@ -106,7 +106,7 @@
    */
   public static function getSubscribedEvents() {
     $events[KernelEvents::REQUEST][] = ['onKernelRequestLanguage', 255];
-    $events[DrupalKernelInterface::CONTAINER_INITIALIZE_FINISHED][] = array('onContainerInitializeFinished', 255);
+    $events[DrupalKernelInterface::CONTAINER_INITIALIZE_SUBREQUEST_FINISHED][] = ['onContainerInitializeSubrequestFinished', 255];
 
     return $events;
   }