diff --git a/main/exercise/admin.php b/main/exercise/admin.php
index 86a5e2b89f..87a18b46a9 100755
--- a/main/exercise/admin.php
+++ b/main/exercise/admin.php
@@ -139,11 +139,9 @@ if (!empty($_GET['action']) && $_GET['action'] == 'exportqti2' && !empty($_GET['
 
 // Exercise object creation.
 if (!is_object($objExercise)) {
-    // construction of the Exercise object
-    $objExercise = new Exercise();
-
     // creation of a new exercise if wrong or not specified exercise ID
     if ($exerciseId) {
+        $objExercise = new Exercise();
         $parseQuestionList = $showPagination > 0 ? false : true;
         if ($editQuestion) {
             $parseQuestionList = false;
@@ -154,6 +152,12 @@ if (!is_object($objExercise)) {
     // saves the object into the session
     Session::write('objExercise', $objExercise);
 }
+
+if (empty($objExercise)) {
+    header('Location: '.api_get_path(WEB_CODE_PATH).'exercise/exercise.php?'.api_get_cidreq());
+    exit;
+}
+
 // Exercise can be edited in their course.
 if ($objExercise->sessionId != $sessionId) {
     api_not_allowed(true);
diff --git a/main/exercise/question.class.php b/main/exercise/question.class.php
index cb56f01101..942379e9ba 100755
--- a/main/exercise/question.class.php
+++ b/main/exercise/question.class.php
@@ -1827,6 +1827,10 @@ abstract class Question
      */
     public static function displayTypeMenu($objExercise)
     {
+        if (empty($objExercise)) {
+            return '';
+        }
+
         $feedbackType = $objExercise->getFeedbackType();
         $exerciseId = $objExercise->id;
 
diff --git a/main/exercise/unique_answer.class.php b/main/exercise/unique_answer.class.php
index a374e6cc49..f3557cecd0 100755
--- a/main/exercise/unique_answer.class.php
+++ b/main/exercise/unique_answer.class.php
@@ -1,4 +1,5 @@
 <?php
+
 /* For licensing terms, see /license.txt */
 
 use Chamilo\CourseBundle\Entity\CQuizAnswer;
@@ -343,13 +344,25 @@ class UniqueAnswer extends Question
             $weighting = trim($form->getSubmitValue('weighting['.$i.']'));
             $scenario = $form->getSubmitValue('scenario');
 
-            //$list_destination = $form -> getSubmitValue('destination'.$i);
-            //$destination_str = $form -> getSubmitValue('destination'.$i);
+            $try = null;
+            $lp = null;
+            $destination = null;
+            $url = null;
+            if (isset($scenario['try'.$i])) {
+                $try = !empty($scenario['try'.$i]);
+            }
+
+            if (isset($scenario['lp'.$i])) {
+                $lp = $scenario['lp'.$i];
+            }
 
-            $try = !empty($scenario['try'.$i]);
-            $lp = $scenario['lp'.$i];
-            $destination = $scenario['destination'.$i];
-            $url = trim($scenario['url'.$i]);
+            if (isset($scenario['destination'.$i])) {
+                $destination = $scenario['destination'.$i];
+            }
+
+            if (isset($scenario['url'.$i])) {
+                $url = trim($scenario['url'.$i]);
+            }
 
             /*
             How we are going to parse the destination value