diff --git a/main/inc/lib/hook/HookEvent.php b/main/inc/lib/hook/HookEvent.php
index 8180b38545..b173b68d06 100644
--- a/main/inc/lib/hook/HookEvent.php
+++ b/main/inc/lib/hook/HookEvent.php
@@ -23,6 +23,7 @@ abstract class HookEvent implements HookEventInterface
     /**
      * Construct Method
      * @param string $eventName
+     *
      * @throws Exception
      */
     protected function __construct($eventName)
diff --git a/main/inc/lib/hook/HookObserver.php b/main/inc/lib/hook/HookObserver.php
index cedfe483c8..226b1ddacb 100644
--- a/main/inc/lib/hook/HookObserver.php
+++ b/main/inc/lib/hook/HookObserver.php
@@ -34,7 +34,7 @@ abstract class HookObserver implements HookObserverInterface
     /**
      * Return the singleton instance of Hook observer.
      * If Hook Management plugin is not enabled, will return NULL
-     * @return static
+     * @return HookObserver
      */
     public static function create()
     {
@@ -45,6 +45,7 @@ abstract class HookObserver implements HookObserverInterface
         } else {
             try {
                 $class = get_called_class();
+
                 return new $class;
 
             } catch (Exception $e) {
diff --git a/plugin/advanced_subscription/src/AdvancedSubscriptionPlugin.php b/plugin/advanced_subscription/src/AdvancedSubscriptionPlugin.php
index a942df8c2a..37edd43aaa 100644
--- a/plugin/advanced_subscription/src/AdvancedSubscriptionPlugin.php
+++ b/plugin/advanced_subscription/src/AdvancedSubscriptionPlugin.php
@@ -1,12 +1,12 @@
 <?php
 /* For licensing terms, see /license.txt */
+
 /**
+ * Class AdvancedSubscriptionPlugin
  * This class is used to add an advanced subscription allowing the admin to
  * create user queues requesting a subscribe to a session
  * @package chamilo.plugin.advanced_subscription
  */
-
-
 class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
 {
     protected $strings;
@@ -64,9 +64,12 @@ class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
      */
     public function uninstall()
     {
-        $this->uninstallHook();
-        // Note: Keeping area field data is intended so it will not be removed
-        $this->uninstallDatabase();
+        $setting = api_get_setting('advanced_subscription');
+        if (!empty($setting)) {
+            $this->uninstallHook();
+            // Note: Keeping area field data is intended so it will not be removed
+            $this->uninstallDatabase();
+        }
     }
 
     /**
@@ -830,6 +833,7 @@ class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
             $count = Database::select('COUNT(*)', $advancedSubscriptionQueueTable, $where);
             $count = $count[0]['COUNT(*)'];
         }
+
         return $count;
     }
 
@@ -863,6 +867,7 @@ class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
      * Return the status from user in queue to session subscription
      * @param int $userId
      * @param int $sessionId
+     *
      * @return bool|int
      */
     public function getQueueStatus($userId, $sessionId)
@@ -969,6 +974,7 @@ class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
             if (isset($sessionArray['banner'])) {
                 $sessionArray['banner'] = api_get_path(WEB_CODE_PATH) . $sessionArray['banner'];
             }
+
             return $sessionArray;
         }
 
@@ -979,13 +985,12 @@ class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
      * Get status message
      * @param int $status
      * @param bool $isAble
+     *
      * @return string
      */
     public function getStatusMessage($status, $isAble = true)
     {
-        $message = '';
-        switch ($status)
-        {
+        switch ($status) {
             case ADVANCED_SUBSCRIPTION_QUEUE_STATUS_NO_QUEUE:
                 if ($isAble) {
                     $message = $this->get_lang('AdvancedSubscriptionNoQueueIsAble');
@@ -1010,7 +1015,6 @@ class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
                 break;
             default:
                 $message = sprintf($this->get_lang('AdvancedSubscriptionQueueDefault'), $status);
-
         }
 
         return $message;
@@ -1019,11 +1023,13 @@ class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
     /**
      * Return the url to go to session
      * @param $sessionId
+     *
      * @return string
      */
     public function getSessionUrl($sessionId)
     {
         $url = api_get_path(WEB_CODE_PATH) . 'session/?session_id=' . intval($sessionId);
+
         return $url;
     }
 
@@ -1044,12 +1050,14 @@ class AdvancedSubscriptionPlugin extends Plugin implements HookPluginInterface
             'is_connected=' . 1 . '&' .
             'profile_completed=' . intval($params['profile_completed']) . '&' .
             'v=' . $this->generateHash($params);
+
         return $url;
     }
 
     /**
      * Return the list of student, in queue used by admin view
      * @param int $sessionId
+     *
      * @return array
      */
     public function listAllStudentsInQueueBySession($sessionId)
diff --git a/plugin/createdrupaluser/src/CreateDrupalUser.php b/plugin/createdrupaluser/src/CreateDrupalUser.php
index 0f41abd815..40924a0e3d 100644
--- a/plugin/createdrupaluser/src/CreateDrupalUser.php
+++ b/plugin/createdrupaluser/src/CreateDrupalUser.php
@@ -9,7 +9,6 @@
  */
 class CreateDrupalUser extends Plugin implements HookPluginInterface
 {
-
     /**
      * Class constructor
      */
@@ -56,8 +55,9 @@ class CreateDrupalUser extends Plugin implements HookPluginInterface
      */
     public function installHook()
     {
-        $hook = HookCreateDrupalUser::create();
-        HookCreateUser::create()->attach($hook);
+        /** @var HookCreateDrupalUser $observer */
+        $observer = HookCreateDrupalUser::create();
+        HookCreateUser::create()->attach($observer);
     }
 
     /**
@@ -65,8 +65,13 @@ class CreateDrupalUser extends Plugin implements HookPluginInterface
      */
     public function uninstallHook()
     {
-        $hook = HookCreateDrupalUser::create();
-        HookCreateUser::create()->detach($hook);
+        /** @var HookCreateDrupalUser $observer */
+        $observer = HookCreateDrupalUser::create();
+        $event = HookCreateUser::create();
+
+        if ($event) {
+            $event->detach($observer);
+        }
     }
 
 }
diff --git a/plugin/createdrupaluser/src/HookCreateDrupalUser.php b/plugin/createdrupaluser/src/HookCreateDrupalUser.php
index 3ae11ca0b2..6c9d21d8af 100644
--- a/plugin/createdrupaluser/src/HookCreateDrupalUser.php
+++ b/plugin/createdrupaluser/src/HookCreateDrupalUser.php
@@ -2,6 +2,7 @@
 /* For licensing terms, see /license.txt */
 
 /**
+ * Class HookCreateDrupalUser
  * Hook to create an user in Drupal website
  *
  * @author Angel Fernando Quiroz Campos <angel.quiroz@beeznest.com>
@@ -9,9 +10,8 @@
  */
 class HookCreateDrupalUser extends HookObserver implements HookCreateUserObserverInterface
 {
-
     /**
-     * Class constructor
+     * Constructor
      */
     public function __construct()
     {