Update to Drupal 8.0.0 beta 14. For more information, see https://drupal.org/node/2544542

core/lib/Drupal/Core/Installer/InstallerKernel.php

@@ -16,13 +16,11 @@ class InstallerKernel extends DrupalKernel {
 
   /**
    * {@inheritdoc}
-   *
-   * @param bool $rebuild
-   *   Force a container rebuild. Unlike the parent method, this defaults to
-   *   TRUE.
    */
-  protected function initializeContainer($rebuild = TRUE) {
-    $container = parent::initializeContainer($rebuild);
+  protected function initializeContainer() {
+    // Always force a container rebuild.
+    $this->containerNeedsRebuild = TRUE;
+    $container = parent::initializeContainer();
     return $container;
   }
 

core/lib/Drupal/Core/Installer/InstallerServiceProvider.php

@@ -46,6 +46,8 @@ class InstallerServiceProvider implements ServiceProviderInterface, ServiceModif
     $container
       ->register('url_generator', 'Drupal\Core\Routing\NullGenerator')
       ->addArgument(new Reference('request_stack'));
+    $container
+      ->register('path_processor_manager', 'Drupal\Core\PathProcessor\NullPathProcessorManager');
     $container
       ->register('router.dumper', 'Drupal\Core\Routing\NullMatcherDumper');
 
@@ -58,7 +60,10 @@ class InstallerServiceProvider implements ServiceProviderInterface, ServiceModif
     // Replace the route builder with an empty implementation.
     // @todo Convert installer steps into routes; add an installer.routing.yml.
     $definition = $container->getDefinition('router.builder');
-    $definition->setClass('Drupal\Core\Installer\InstallerRouteBuilder');
+    $definition->setClass('Drupal\Core\Installer\InstallerRouteBuilder')
+      // The core router builder, but there is no reason here to be lazy, so
+      // we don't need to ship with a custom proxy class.
+      ->setLazy(FALSE);
   }
 
   /**