diff --git a/main/inc/lib/tracking.lib.php b/main/inc/lib/tracking.lib.php
index 141841b7ab..b77bf6eb8c 100755
--- a/main/inc/lib/tracking.lib.php
+++ b/main/inc/lib/tracking.lib.php
@@ -1121,8 +1121,10 @@ class Tracking
                 STUDENT
             );
             $students = array();
-            foreach ($studentList as $studentData) {
-                $students[] = $studentData['user_id'];
+            if (is_array($studentList)) {
+                foreach ($studentList as $studentData) {
+                    $students[] = $studentData['user_id'];
+                }
             }
 
             $studentBossesList = SessionManager::getAllUsersFromCoursesFromAllSessionFromStatus(
@@ -1141,8 +1143,10 @@ class Tracking
                 STUDENT_BOSS
             );
             $studentBosses = array();
-            foreach ($studentBossesList as $studentBossData) {
-                $studentBosses[] = $studentBossData['user_id'];
+            if (is_array($studentBossesList)) {
+                foreach ($studentBossesList as $studentBossData) {
+                    $studentBosses[] = $studentBossData['user_id'];
+                }
             }
 
             $teacherList = SessionManager::getAllUsersFromCoursesFromAllSessionFromStatus(
@@ -1182,8 +1186,10 @@ class Tracking
             );
 
             $humanResourcesList = array();
-            foreach ($humanResources as $item) {
-                $humanResourcesList[] = $item['user_id'];
+            if (is_array($humanResources)) {
+                foreach ($humanResources as $item) {
+                    $humanResourcesList[] = $item['user_id'];
+                }
             }
 
             $platformCourses = SessionManager::getAllCoursesFollowedByUser(
@@ -1772,7 +1778,11 @@ class Tracking
 
     		$sql = "SELECT count(id) FROM $tbl_course_quiz
     				WHERE c_id = {$course_info['real_id']} $condition_active $condition_quiz ";
-    		$count_quiz = Database::fetch_row(Database::query($sql));
+            $count_quiz = 0;
+            $countQuizResult = Database::query($sql);
+            if (!empty($countQuizResult)) {
+                $count_quiz = Database::fetch_row($countQuizResult);
+            }
 
     		if (!empty($count_quiz[0]) && !empty($student_id)) {
     			if (is_array($student_id)) {
@@ -1789,7 +1799,7 @@ class Tracking
                     $result = Database::query($sql);
                     $exercise_list = array();
     				$exercise_id = null;
-                    if (Database::num_rows($result)) {
+                    if (!empty($result) && Database::num_rows($result)) {
                         while ($row = Database::fetch_array($result)) {
                             $exercise_list[] = $row['id'];
                         }
@@ -4686,7 +4696,10 @@ class Tracking
                     }
                     //Score
                     $html .= Display::tag('td', $percentage_score, array('align'=>'center'));
-                    $html .= Display::tag('td', $last_connection,  array('align'=>'center'));
+                    if (empty($last_connection) or is_bool($last_connection)) {
+                        $last_connection = '';
+                    }
+                    $html .= Display::tag('td', $last_connection, array('align' => 'center'));
 
                     if ($course_code == $courseCodeFromGet && $_GET['session_id'] == $session_id_from_get) {
                         $details = '<a href="#">';
@@ -4852,6 +4865,9 @@ class Tracking
                                     $my_score = $score/$weighting;
                                 }
                                 //@todo this function slows the page
+                                if (is_int($user_list)) {
+                                    $user_list = array($user_list);
+                                }
                                 $position = ExerciseLib::get_exercise_result_ranking($my_score, $exe_id, $exercices['id'], $course_info['code'], $session_id, $user_list);
 
                                 $graph = self::generate_exercise_result_thumbnail_graph($to_graph_exercise_result[$exercices['id']]);
@@ -5527,7 +5543,8 @@ class Tracking
      * @param   int $sessionId  The session ID (session.id)
      * @param   int $courseId   The course ID (course.id)
      * @param   int $exerciseId The quiz ID (c_quiz.id)
-     * @param   int $answer     The answer status (0 = incorrect, 1 = correct, 2 = both)
+     * @param   string $date_from
+     * @param   string $date_to
      * @param   array   $options    An array of options you can pass to the query (limit, where and order)
      * @return array An array with the data of exercise(s) progress
      */
diff --git a/main/inc/lib/usermanager.lib.php b/main/inc/lib/usermanager.lib.php
index 1c0c44143d..71fbd62749 100755
--- a/main/inc/lib/usermanager.lib.php
+++ b/main/inc/lib/usermanager.lib.php
@@ -2270,7 +2270,7 @@ class UserManager
     /**
      * Get all the extra field information of a certain field (also the options)
      *
-     * @param int $field_name the name of the field we want to know everything of
+     * @param int $fieldId the ID of the field we want to know everything of
      * @return array $return containing all th information about the extra profile field
      * @author Julio Montoya
      * @deprecated