diff --git a/public/main/admin/add_courses_to_usergroup.php b/public/main/admin/add_courses_to_usergroup.php
index b63db1e27c..1b7fceb157 100644
--- a/public/main/admin/add_courses_to_usergroup.php
+++ b/public/main/admin/add_courses_to_usergroup.php
@@ -281,7 +281,6 @@ echo Display::select(
     ['style' => 'width:360px', 'multiple' => 'multiple', 'id' => 'elements_in', 'size' => '15px'],
     false
 );
-unset($sessionUsersList);
 ?>
  </td>
 </tr>
diff --git a/public/main/admin/add_sessions_to_promotion.php b/public/main/admin/add_sessions_to_promotion.php
index c4db603768..19ce2b3b80 100644
--- a/public/main/admin/add_sessions_to_promotion.php
+++ b/public/main/admin/add_sessions_to_promotion.php
@@ -1,4 +1,5 @@
 <?php
+
 /* For licensing terms, see /license.txt */
 
 // resetting the course id
@@ -235,7 +236,6 @@ if (!empty($errorMsg)) {
         ['style' => 'width:360px', 'multiple' => 'multiple', 'id' => 'session_in_promotion', 'size' => '15px'],
         false
     );
-    unset($sessionUsersList);
 ?>
  </td>
 </tr>
diff --git a/public/main/admin/add_sessions_to_usergroup.php b/public/main/admin/add_sessions_to_usergroup.php
index 6d3e24fcfc..e54377fdaa 100644
--- a/public/main/admin/add_sessions_to_usergroup.php
+++ b/public/main/admin/add_sessions_to_usergroup.php
@@ -1,4 +1,5 @@
 <?php
+
 /* For licensing terms, see /license.txt */
 
 // resetting the course id
@@ -263,7 +264,6 @@ echo Display::select(
     ['style' => 'width:360px', 'multiple' => 'multiple', 'id' => 'elements_in', 'size' => '15px'],
     false
 );
-    unset($sessionUsersList);
 ?>
  </td>
 </tr>
diff --git a/public/main/admin/add_users_to_usergroup.php b/public/main/admin/add_users_to_usergroup.php
index efcf642b6d..228e6ac591 100644
--- a/public/main/admin/add_users_to_usergroup.php
+++ b/public/main/admin/add_users_to_usergroup.php
@@ -1,4 +1,5 @@
 <?php
+
 /* For licensing terms, see /license.txt */
 
 // resetting the course id
@@ -60,7 +61,7 @@ function validate_filter() {
     document.formulaire.submit();
 }
 
-function checked_in_no_group(checked) 
+function checked_in_no_group(checked)
 {
     $("#relation")
     .find("option")
@@ -453,7 +454,6 @@ echo Display::input('hidden', 'add_type', null);
             ],
             false
         );
-        unset($sessionUsersList);
     ?>
     </div>
 </div>
diff --git a/public/main/admin/configure_inscription.php b/public/main/admin/configure_inscription.php
index e5f62b93fe..b26d9270af 100644
--- a/public/main/admin/configure_inscription.php
+++ b/public/main/admin/configure_inscription.php
@@ -346,14 +346,13 @@ $url = api_get_path(WEB_PUBLIC_PATH).'internal_page/edit/inscription';
 //Form of language
 //$content .= api_display_language_form();
 $content .= '&nbsp;&nbsp;<a href="'.api_get_self().'?action=edit_top">'.
-    Display::return_icon('edit.gif', get_lang('Edit')).'</a> 
+    Display::return_icon('edit.gif', get_lang('Edit')).'</a>
     <a href="'.$url.'">'.get_lang('Edit notice').'</a>';
 
 $content .= $form->returnForm();
 
-$page = Container::getPage('inscription');
-
-$tpl->assign('page', $page);
+//$page = Container::getPage('inscription');
+//$tpl->assign('page', $page);
 $tpl->assign('form', $content);
 
 $templateName = $tpl->get_template('auth/inscription_edit.html.twig');
diff --git a/public/main/admin/configure_plugin.php b/public/main/admin/configure_plugin.php
index ff2838ab69..8256afb039 100644
--- a/public/main/admin/configure_plugin.php
+++ b/public/main/admin/configure_plugin.php
@@ -69,7 +69,7 @@ if (isset($form)) {
         foreach ($values as $key => $value) {
             api_add_setting(
                 $value,
-                Database::escape_string($pluginName.'_'.$key),
+                $pluginName.'_'.$key,
                 $pluginName,
                 'setting',
                 'Plugins',
@@ -81,12 +81,13 @@ if (isset($form)) {
                 1
             );
         }
+
         Event::addEvent(
             LOG_PLUGIN_CHANGE,
             LOG_PLUGIN_SETTINGS_CHANGE,
             $pluginName,
             api_get_utc_datetime(),
-            $user_id
+            api_get_user_id()
         );
 
         if (!empty($pluginInfo['plugin_class'])) {
diff --git a/public/main/admin/course_category.php b/public/main/admin/course_category.php
index fcdafeb518..ea0dec54e9 100644
--- a/public/main/admin/course_category.php
+++ b/public/main/admin/course_category.php
@@ -23,13 +23,13 @@ $action = isset($_GET['action']) ? $_GET['action'] : null;
 $myCourseListAsCategory = api_get_configuration_value('my_courses_list_as_category');
 
 if (!empty($action)) {
-    if ('delete' == $action) {
+    if ('delete' === $action) {
         CourseCategory::deleteNode($categoryId);
         Display::addFlash(Display::return_message(get_lang('Deleted')));
         header('Location: '.api_get_self().'?category='.Security::remove_XSS($category));
         exit();
-    } elseif (('add' == $action || 'edit' == $action) && isset($_POST['formSent']) && $_POST['formSent']) {
-        if ('add' == $action) {
+    } elseif (('add' == $action || 'edit' === $action) && isset($_POST['formSent']) && $_POST['formSent']) {
+        if ('add' === $action) {
             $ret = CourseCategory::addNode(
                 $_POST['code'],
                 $_POST['name'],
diff --git a/public/main/admin/course_edit.php b/public/main/admin/course_edit.php
index b1102bfdde..30fccb5e1e 100644
--- a/public/main/admin/course_edit.php
+++ b/public/main/admin/course_edit.php
@@ -154,8 +154,7 @@ if ($countCategories >= 100) {
     // Category code
     $url = api_get_path(WEB_AJAX_PATH).'course.ajax.php?a=search_category';
 
-    $categorySelect = $form->addElement(
-        'select_ajax',
+    $categorySelect = $form->addSelectAjax(
         'category_id',
         get_lang('Category'),
         null,
diff --git a/public/main/admin/index.php b/public/main/admin/index.php
index 073d2ac87f..fb7319f7d1 100644
--- a/public/main/admin/index.php
+++ b/public/main/admin/index.php
@@ -541,42 +541,6 @@ if (api_is_platform_admin()) {
     $blocks['version_check']['search_form'] = null;
     $blocks['version_check']['items'] = '<div class="block-admin-version_check"></div>';
     $blocks['version_check']['class'] = '';
-
-    // Check Hook Event for Admin Block Object
-    if (!empty($hook)) {
-        // If not empty, then notify Post process to Hook Observers for Admin Block
-        $hook->setEventData(['blocks' => $blocks]);
-        $data = $hook->notifyAdminBlock(HOOK_EVENT_TYPE_POST);
-        // Check if blocks data is not null
-        if (isset($data['blocks'])) {
-            // Get modified blocks
-            $blocks = $data['blocks'];
-        }
-    }
-
-    //Hack for fix migration on session_rel_user
-    $tableColumns = Database::getManager()
-        ->getConnection()
-        ->getSchemaManager()
-        ->listTableColumns(
-            Database::get_main_table(TABLE_MAIN_SESSION_USER)
-        );
-
-    if (!array_key_exists('duration', $tableColumns)) {
-        try {
-            $dbSchema = Database::getManager()->getConnection()->getSchemaManager();
-            $durationColumn = new \Doctrine\DBAL\Schema\Column(
-                'duration',
-                Doctrine\DBAL\Types\Type::getType(\Doctrine\DBAL\Types\Type::INTEGER),
-                ['notnull' => false]
-            );
-            $tableDiff = new \Doctrine\DBAL\Schema\TableDiff('session_rel_user', [$durationColumn]);
-            $dbSchema->alterTable($tableDiff);
-        } catch (Exception $e) {
-            error_log($e->getMessage());
-        }
-    }
-    //end hack
 }
 $admin_ajax_url = api_get_path(WEB_AJAX_PATH).'admin.ajax.php';
 
diff --git a/src/CoreBundle/Controller/SessionController.php b/src/CoreBundle/Controller/SessionController.php
index f2f62f9b4c..a5922490fa 100644
--- a/src/CoreBundle/Controller/SessionController.php
+++ b/src/CoreBundle/Controller/SessionController.php
@@ -192,8 +192,6 @@ class SessionController extends AbstractController
             }
         }
 
-        $courseController = new CoursesController();
-
         $plugin = \BuyCoursesPlugin::create();
         $checker = $plugin->isEnabled();
         $sessionIsPremium = null;
@@ -235,7 +233,7 @@ class SessionController extends AbstractController
                 $session->getId(),
                 api_get_user_id()
             ),
-            'subscribe_button' => $courseController->getRegisteredInSessionButton(
+            'subscribe_button' => \CoursesAndSessionsCatalog::getRegisteredInSessionButton(
                 $session->getId(),
                 $session->getName(),
                 $hasRequirements,
diff --git a/src/CoreBundle/Framework/Container.php b/src/CoreBundle/Framework/Container.php
index 30eb7eea3d..de1fedabdd 100644
--- a/src/CoreBundle/Framework/Container.php
+++ b/src/CoreBundle/Framework/Container.php
@@ -5,7 +5,6 @@
 namespace Chamilo\CoreBundle\Framework;
 
 use Chamilo\CoreBundle\Component\Editor\Editor;
-use Chamilo\CoreBundle\Hook\Interfaces\HookEventInterface;
 use Chamilo\CoreBundle\Manager\SettingsManager;
 use Chamilo\CoreBundle\Repository\AccessUrlRepository;
 use Chamilo\CoreBundle\Repository\CourseCategoryRepository;
@@ -37,7 +36,6 @@ use Chamilo\CourseBundle\Repository\CShortcutRepository;
 use Chamilo\CourseBundle\Repository\CStudentPublicationAssignmentRepository;
 use Chamilo\CourseBundle\Repository\CStudentPublicationCommentRepository;
 use Chamilo\CourseBundle\Repository\CStudentPublicationRepository;
-use Chamilo\PageBundle\Entity\Page;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Session\Session;
diff --git a/src/CoreBundle/Hook/HookManagement.php b/src/CoreBundle/Hook/HookManagement.php
index fdae38806a..b65bbf0467 100644
--- a/src/CoreBundle/Hook/HookManagement.php
+++ b/src/CoreBundle/Hook/HookManagement.php
@@ -12,7 +12,7 @@ use Doctrine\ORM\EntityManager;
 /**
  * @TODO: Improve description
  */
-class HookManagement implements HookManagementInterface
+class HookManagement
 {
     private $entityManager;
 
@@ -132,8 +132,8 @@ class HookManagement implements HookManagementInterface
      *
      * @return int
      */
-    public function orderHook($eventName, $type, $hookOrders)
-    {
+    //public function orderHook($eventName, $type, $hookOrders)
+    //{
         /*foreach ($this->hookCalls[$eventName] as $observerClassName => $types) {
             foreach ($hookOrders as $oldOrder => $newOrder) {
                 $res = Database::update(
@@ -152,7 +152,7 @@ class HookManagement implements HookManagementInterface
                 }
             }
         }*/
-    }
+    //}
 
     /**
      * Return a list an associative array where keys are the active hook observer class name.