diff -u b/core/core.services.yml b/core/core.services.yml
--- b/core/core.services.yml
+++ b/core/core.services.yml
@@ -66,7 +66,7 @@
     arguments: ['@database', '@cache_tags.invalidator.checksum']
   cache.backend.apcu:
     class: Drupal\Core\Cache\ApcuBackendFactory
-    arguments: ['@app.root', '@kernel', '@cache_tags.invalidator.checksum']
+    arguments: ['@app.root', '@cache_tags.invalidator.checksum']
   cache.backend.php:
     class: Drupal\Core\Cache\PhpBackendFactory
     arguments: ['@cache_tags.invalidator.checksum']
@@ -136,7 +136,7 @@
     arguments: ['@database', '@cache_tags.invalidator.checksum']
   cache.backend.apcu:
     class: Drupal\Core\Cache\ApcuBackendFactory
-    arguments: ['@app.root', '@cache_tags.invalidator.checksum']
+    arguments: ['@app.root', '@kernel', '@cache_tags.invalidator.checksum']
   cache.backend.php:
     class: Drupal\Core\Cache\PhpBackendFactory
     arguments: ['@cache_tags.invalidator.checksum']
@@ -542,6 +542,16 @@
     class: Drupal\Core\AppRootFactory
     arguments: ['@kernel']
     public: false
+  site.path:
+    class: SplString
+    factory_service: 'site.path.factory'
+    factory_method: 'get'
+    tags:
+      - { name: parameter_service }
+  site.path.factory:
+    class: Drupal\Core\SitePathFactory
+    arguments: ['@kernel']
+    public: false
   controller_resolver:
     class: Drupal\Core\Controller\ControllerResolver
     arguments: ['@class_resolver']
only in patch2:
unchanged:
--- /dev/null
+++ b/core/lib/Drupal/Core/SitePathFactory.php
@@ -0,0 +1,43 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\SitePathFactory.
+ */
+
+namespace Drupal\Core;
+
+/**
+ * Gets the site path from the kernel.
+ */
+class SitePathFactory {
+
+  /**
+   * The Drupal kernel.
+   *
+   * @var \Drupal\Core\DrupalKernelInterface
+   */
+  protected $drupalKernel;
+
+  /**
+   * Constructs an SitePathFactory instance.
+   *
+   * @param \Drupal\Core\DrupalKernelInterface $drupal_kernel
+   *   The Drupal kernel.
+   */
+  public function __construct(DrupalKernelInterface $drupal_kernel) {
+    $this->drupalKernel = $drupal_kernel;
+  }
+
+  /**
+   * Gets the app root.
+   *
+   * @return string
+   *   The site path.
+   */
+  public function get() {
+    return $this->drupalKernel->getSitePath();
+  }
+
+}
+