diff -u b/core/lib/Drupal/Core/Render/Element/Link.php b/core/lib/Drupal/Core/Render/Element/Link.php
--- b/core/lib/Drupal/Core/Render/Element/Link.php
+++ b/core/lib/Drupal/Core/Render/Element/Link.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Render\Element;
 
-use Drupal\Component\Utility\Html;
 use Drupal\Component\Utility\NestedArray;
 
 /**
@@ -70,7 +69,7 @@
     if (isset($element['#ajax']) && !isset($element['#ajax_processed'])) {
       // If no HTML ID was found above, automatically create one.
       if (!isset($element['#id'])) {
-        $element['#id'] = $element['#options']['attributes']['id'] = Html::getUniqueId('ajax-link');
+        $element['#id'] = $element['#options']['attributes']['id'] = \Drupal\Component\Utility\Html::getUniqueId('ajax-link');
       }
       $element = static::preRenderAjaxForm($element);
     }
diff -u b/core/lib/Drupal/Core/Render/Element/Radios.php b/core/lib/Drupal/Core/Render/Element/Radios.php
--- b/core/lib/Drupal/Core/Render/Element/Radios.php
+++ b/core/lib/Drupal/Core/Render/Element/Radios.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Render\Element;
 
-use Drupal\Component\Utility\Html;
 use Drupal\Core\Form\FormStateInterface;
 
 /**
@@ -66,7 +65,7 @@
           '#default_value' => isset($element['#default_value']) ? $element['#default_value'] : FALSE,
           '#attributes' => $element['#attributes'],
           '#parents' => $element['#parents'],
-          '#id' => Html::getUniqueId('edit-' . implode('-', $parents_for_id)),
+          '#id' => \Drupal\Component\Utility\Html::getUniqueId('edit-' . implode('-', $parents_for_id)),
           '#ajax' => isset($element['#ajax']) ? $element['#ajax'] : NULL,
           '#weight' => $weight,
         );
diff -u b/core/lib/Drupal/Core/Render/Element/Table.php b/core/lib/Drupal/Core/Render/Element/Table.php
--- b/core/lib/Drupal/Core/Render/Element/Table.php
+++ b/core/lib/Drupal/Core/Render/Element/Table.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Render\Element;
 
-use Drupal\Component\Utility\Html;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Render\Element;
 
@@ -173,7 +172,7 @@
           $row = array('select' => array()) + $row;
           $row['select'] += array(
             '#type' => $element['#multiple'] ? 'checkbox' : 'radio',
-            '#id' => Html::getUniqueId('edit-' . implode('-', $element_parents)),
+            '#id' => \Drupal\Component\Utility\Html::getUniqueId('edit-' . implode('-', $element_parents)),
             // @todo If rows happen to use numeric indexes instead of string keys,
             //   this results in a first row with $key === 0, which is always FALSE.
             '#return_value' => $key,
diff -u b/core/lib/Drupal/Core/Render/Element/Tableselect.php b/core/lib/Drupal/Core/Render/Element/Tableselect.php
--- b/core/lib/Drupal/Core/Render/Element/Tableselect.php
+++ b/core/lib/Drupal/Core/Render/Element/Tableselect.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Render\Element;
 
-use Drupal\Component\Utility\Html;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Render\Element;
 
@@ -237,7 +236,7 @@
               '#default_value' => ($element['#default_value'] == $key) ? $key : NULL,
               '#attributes' => $element['#attributes'],
               '#parents' => $element['#parents'],
-              '#id' => Html::getUniqueId('edit-' . implode('-', $parents_for_id)),
+              '#id' => \Drupal\Component\Utility\Html::getUniqueId('edit-' . implode('-', $parents_for_id)),
               '#ajax' => isset($element['#ajax']) ? $element['#ajax'] : NULL,
             );
           }
only in patch2:
unchanged:
--- a/core/install.php
+++ b/core/install.php
@@ -7,7 +7,9 @@
 
 // Change the directory to the Drupal root.
 chdir('..');
-
+error_reporting(E_ALL);
+ini_set('display_errors', TRUE);
+ini_set('display_startup_errors', TRUE);
 /**
  * Global flag to indicate the site is in installation mode.
  *
only in patch2:
unchanged:
--- a/index.php
+++ b/index.php
@@ -16,6 +16,10 @@
 
 $autoloader = require_once __DIR__ . '/core/vendor/autoload.php';
 
+error_reporting(E_ALL);
+ini_set('display_errors', TRUE);
+ini_set('display_startup_errors', TRUE);
+
 try {
 
   $request = Request::createFromGlobals();