diff --git a/public/main/course_progress/index.php b/public/main/course_progress/index.php
index 8a865dfc6e..4a82bb4afa 100644
--- a/public/main/course_progress/index.php
+++ b/public/main/course_progress/index.php
@@ -17,6 +17,7 @@ $current_course_tool = TOOL_COURSE_PROGRESS;
 // protect a course script
 api_protect_course_script(true);
 $courseId = api_get_course_int_id();
+$description_type = null;
 
 // get actions
 $actions = [
@@ -132,7 +133,6 @@ $interbreadcrumb[] = [
 ];
 
 $actionLeft = '';
-
 // instance thematic object for using like library here
 $thematicManager = new Thematic();
 
@@ -724,10 +724,10 @@ switch ($action) {
         } else {
             $header_form = $default_thematic_plan_title[$description_type];
         }
-        if (!$error) {
+        /*if (!$error) {
             $token = md5(uniqid(rand(), true));
             Session::write('thematic_plan_token', $token);
-        }
+        }*/
 
         // display form
         $form = new FormValidator(
@@ -779,7 +779,7 @@ switch ($action) {
         }
 
         // error messages
-        if ($error) {
+        /*if ($error) {
             Display::addFlash(
                 Display::return_message(
                     get_lang('The form contains incorrect or incomplete data. Please check your input.'),
@@ -787,7 +787,7 @@ switch ($action) {
                     false
                 )
             );
-        }
+        }*/
         $content = $form->returnForm();
         break;
     case 'thematic_plan_delete':
diff --git a/public/main/exercise/admin.php b/public/main/exercise/admin.php
index 229e62fa2b..f9e575eabb 100644
--- a/public/main/exercise/admin.php
+++ b/public/main/exercise/admin.php
@@ -106,12 +106,12 @@ if (isset($_REQUEST['convertAnswer'])) {
 $objAnswer = Session::read('objAnswer');
 $_course = api_get_course_info();
 
-// tables used in the exercise tool
-if (!empty($_GET['action']) && 'exportqti2' == $_GET['action'] && !empty($_GET['questionId'])) {
+// tables used in the exercise tool.
+if (!empty($_GET['action']) && 'exportqti2' === $_GET['action'] && !empty($_GET['questionId'])) {
     require_once 'export/qti2/qti2_export.php';
     $export = export_question_qti($_GET['questionId'], true);
     $qid = (int) $_GET['questionId'];
-
+    $name = 'qti2_export_'.$qid.'.zip';
     $zip = api_create_zip($name);
     $zip->addFile("qti2export_$qid.xml", $export);
     $zip->finish();
diff --git a/public/main/exercise/aiken.php b/public/main/exercise/aiken.php
index a63b2347c0..44294b2f6c 100644
--- a/public/main/exercise/aiken.php
+++ b/public/main/exercise/aiken.php
@@ -12,12 +12,8 @@ require_once __DIR__.'/../inc/global.inc.php';
 
 api_protect_course_script(true);
 
-$lib_path = api_get_path(LIBRARY_PATH);
-$main_path = api_get_path(SYS_CODE_PATH);
-
-// including additional libraries
-require_once $main_path.'exercise/export/aiken/aiken_import.inc.php';
-require_once $main_path.'exercise/export/aiken/aiken_classes.php';
+require_once __DIR__.'/export/aiken/aiken_import.inc.php';
+require_once __DIR__.'/export/aiken/aiken_classes.php';
 
 // section (for the tabs)
 $this_section = SECTION_COURSES;
@@ -44,11 +40,6 @@ if (api_is_allowed_to_edit(null, true)) {
     }
 }
 
-// display header
 Display::display_header(get_lang('Import Aiken quiz'), 'Exercises');
-
-// display Aiken form
 aiken_display_form();
-
-// display the footer
 Display::display_footer();
diff --git a/public/main/exercise/exercise.php b/public/main/exercise/exercise.php
index 6aef80049e..0eacb3eb26 100644
--- a/public/main/exercise/exercise.php
+++ b/public/main/exercise/exercise.php
@@ -231,7 +231,7 @@ if ($is_allowedToEdit && !empty($action)) {
             if ($limitTeacherAccess && !api_is_platform_admin()) {
                 api_not_allowed(true);
             }
-            require_once api_get_path(SYS_CODE_PATH).'exercise/export/qti2/qti2_export.php';
+            require_once __DIR__.'/export/qti2/qti2_export.php';
             $export = export_exercise_to_qti($exerciseId, true);
 
             $xmlReader = new XMLReader();
diff --git a/public/main/exercise/exercise_report.php b/public/main/exercise/exercise_report.php
index 29d51037f5..02789bed3d 100644
--- a/public/main/exercise/exercise_report.php
+++ b/public/main/exercise/exercise_report.php
@@ -203,7 +203,11 @@ if (isset($_REQUEST['comments']) &&
         }
 
         // From the database.
-        $marksFromDatabase = $questionListData[$questionId]['marks'];
+        $marksFromDatabase = 0;
+        if (isset($questionListData[$questionId])) {
+            $marksFromDatabase = $questionListData[$questionId]['marks'];
+        }
+
         if (in_array($question->type, [FREE_ANSWER, ORAL_EXPRESSION, ANNOTATION])) {
             // From the form.
             $params['marks'] = $marks;
@@ -232,11 +236,11 @@ if (isset($_REQUEST['comments']) &&
         $recording = new TrackEAttemptRecording();
         $recording
             ->setExeId($id)
-            ->setQuestionId($my_questionid)
+            ->setQuestionId($questionId)
             ->setAuthor(api_get_user_id())
             ->setTeacherComment($my_comments)
             ->setExeId($id)
-            ->setMarks($my_marks)
+            ->setMarks($marks)
             ->setSessionId(api_get_session_id())
         ;
 
diff --git a/public/main/exercise/exercise_show.php b/public/main/exercise/exercise_show.php
index 376cfd33de..1382c949b2 100644
--- a/public/main/exercise/exercise_show.php
+++ b/public/main/exercise/exercise_show.php
@@ -570,7 +570,7 @@ foreach ($questionList as $questionId) {
                     <script>
                         AnnotationQuestion({
                             questionId: '.(int) $questionId.',
-                            exerciseId: '.(int) $id.',
+                            exerciseId: '.$id.',
                             relPath: \''.$relPath.'\',
                             courseId: '.(int) $courseInfo['real_id'].'
                         });
@@ -850,14 +850,12 @@ foreach ($questionList as $questionId) {
             $countPendingQuestions++;
         }
     }
-
-    unset($objAnswerTmp);
     $i++;
 
     $contents = ob_get_clean();
     $question_content = '<div class="question_row">';
     if ($show_results && $objQuestionTmp) {
-        $objQuestionTmp->export = 'export' == $action;
+        $objQuestionTmp->export = 'export' === $action;
         // Shows question title an description
         $question_content .= $objQuestionTmp->return_header(
             $objExercise,
diff --git a/public/main/exercise/exercise_submit.php b/public/main/exercise/exercise_submit.php
index 337388df39..5b1030bea3 100644
--- a/public/main/exercise/exercise_submit.php
+++ b/public/main/exercise/exercise_submit.php
@@ -1136,7 +1136,8 @@ if ($limit_time_exists) {
 }
 
 // Blocking empty start times see BT#2800
-global $_custom;
+// @todo use api_get_configuration_value()
+/*global $_custom;
 if (isset($_custom['exercises_hidden_when_no_start_date']) &&
     $_custom['exercises_hidden_when_no_start_date']
 ) {
@@ -1154,7 +1155,7 @@ if (isset($_custom['exercises_hidden_when_no_start_date']) &&
             exit;
         }
     }
-}
+}*/
 
 if ($time_control) {
     echo $objExercise->returnTimeLeftDiv();
diff --git a/public/main/exercise/export/qti2/Ims2Question.php b/public/main/exercise/export/qti2/Ims2Question.php
index ead88bbb8b..ce002bb141 100644
--- a/public/main/exercise/export/qti2/Ims2Question.php
+++ b/public/main/exercise/export/qti2/Ims2Question.php
@@ -17,6 +17,7 @@ class Ims2Question extends Question
     public function setAnswer()
     {
         switch ($this->type) {
+            case TF:
             case MCUA:
                 $answer = new ImsAnswerMultipleChoice($this->id);
 
@@ -24,10 +25,6 @@ class Ims2Question extends Question
             case MCMA:
                 $answer = new ImsAnswerMultipleChoice($this->id);
 
-                return $answer;
-            case TF:
-                $answer = new ImsAnswerMultipleChoice($this->id);
-
                 return $answer;
             case FIB:
                 $answer = new ImsAnswerFillInBlanks($this->id);
diff --git a/public/main/exercise/hotspot_actionscript.as.php b/public/main/exercise/hotspot_actionscript.as.php
index d72e6e9909..949f65242c 100644
--- a/public/main/exercise/hotspot_actionscript.as.php
+++ b/public/main/exercise/hotspot_actionscript.as.php
@@ -113,7 +113,7 @@ $attemptInfo = Database::select(
     [
         'where' => [
             'exe_exo_id = ? AND c_id = ? AND exe_user_id = ? AND status = ?' => [
-                (int) $exerciseId,
+                $exerciseId,
                 $course_id,
                 api_get_user_id(),
                 'incomplete',
diff --git a/public/main/inc/lib/api.lib.php b/public/main/inc/lib/api.lib.php
index ded76669a4..f7bbf07245 100644
--- a/public/main/inc/lib/api.lib.php
+++ b/public/main/inc/lib/api.lib.php
@@ -18,6 +18,8 @@ use Symfony\Component\Finder\Finder;
 use Symfony\Component\Mime\Address;
 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 use Symfony\Component\Security\Core\User\UserInterface;
+use ZipStream\Option\Archive;
+use ZipStream\ZipStream;
 
 /**
  * This is a code library for Chamilo.
@@ -8434,18 +8436,16 @@ function api_get_language_list_for_flag()
 /**
  * @param string $name
  *
- * @return \ZipStream\ZipStream
+ * @return ZipStream
  */
 function api_create_zip($name)
 {
-    $zipStreamOptions = new \ZipStream\Option\Archive();
+    $zipStreamOptions = new Archive();
     $zipStreamOptions->setSendHttpHeaders(true);
     $zipStreamOptions->setContentDisposition('attachment');
     $zipStreamOptions->setContentType('application/x-zip');
 
-    $zip = new \ZipStream\ZipStream($name, $zipStreamOptions);
-
-    return $zip;
+    return new ZipStream($name, $zipStreamOptions);
 }
 
 /**
diff --git a/public/main/inc/lib/course_description.lib.php b/public/main/inc/lib/course_description.lib.php
index 7c44d69c1b..35063fe6a3 100644
--- a/public/main/inc/lib/course_description.lib.php
+++ b/public/main/inc/lib/course_description.lib.php
@@ -2,6 +2,9 @@
 
 /* For licensing terms, see /license.txt */
 
+use Chamilo\CoreBundle\Framework\Container;
+use Chamilo\CourseBundle\Entity\CCourseDescription;
+
 /**
  * This file contains a class used like library provides functions for
  * course description tool. It's also used like model to
@@ -9,13 +12,6 @@
  *
  * @author Christian Fasanando <christian1827@gmail.com>
  */
-
-use Chamilo\CoreBundle\Framework\Container;
-use Chamilo\CourseBundle\Entity\CCourseDescription;
-
-/**
- * Class CourseDescription course descriptions.
- */
 class CourseDescription
 {
     private $id;
@@ -26,9 +22,6 @@ class CourseDescription
     private $description_type;
     private $progress;
 
-    /**
-     * Constructor.
-     */
     public function __construct()
     {
     }
@@ -115,7 +108,7 @@ class CourseDescription
      * first you must set session_id property with the object CourseDescription.
      *
      * @param int    $description_type Description type
-     * @param string $courseId         Course code (optional)
+     * @param int    $courseId         Course code (optional)
      * @param int    $session_id       Session id (optional)
      *
      * @return array List of fields from the descriptions found of the given type