diff --git a/public/main/gradebook/gradebook_add_result.php b/public/main/gradebook/gradebook_add_result.php
index 0d099d1070..3699c642b9 100644
--- a/public/main/gradebook/gradebook_add_result.php
+++ b/public/main/gradebook/gradebook_add_result.php
@@ -43,12 +43,21 @@ if ($add_result_form->validate()) {
     foreach ($scores as $userId => $row) {
         $res = new Result();
         $res->set_evaluation_id($values['evaluation_id']);
-        $res->set_user_id(key($scores));
+        $res->set_user_id($userId);
         //if no scores are given, don't set the score
         if (!empty($row) || '0' == $row) {
             $res->set_score($row);
         }
-        $res->add();
+
+        //To prevent error editing when going back in the browser,
+        //check if exist a record for this user and evaluation_id
+        if ($res->exists()) {
+            $res->addResultLog($userId, $values['evaluation_id']);
+            $res->save();
+        } else {
+            $res->add();
+        }
+
         next($scores);
     }
 
diff --git a/public/main/gradebook/lib/be/result.class.php b/public/main/gradebook/lib/be/result.class.php
index 4af96a5e69..91fedd3dde 100644
--- a/public/main/gradebook/lib/be/result.class.php
+++ b/public/main/gradebook/lib/be/result.class.php
@@ -268,7 +268,14 @@ class Result
         } else {
             $sql .= 'null';
         }
-        $sql .= ' WHERE id = '.$this->id;
+        if (isset($this->id)) {
+            $sql .= " WHERE id = {$this->id}";
+        } else {
+            $sql .= " WHERE evaluation_id = {$this->evaluation}
+                AND user_id = {$this->user_id}
+            ";
+        }
+
         // no need to update creation date
         Database::query($sql);
 
@@ -302,16 +309,15 @@ class Result
      */
     public function exists()
     {
-        $em = Database::getManager();
-
-        $result = $em
-            ->createQuery(
-                'SELECT COUNT(gr) FROM ChamiloCoreBundle:GradebookResult gr
-                WHERE gr.evaluationId = :eval_id AND gr.userId = :user_id'
-            )
-            ->setParameters(['eval_id' => $this->evaluation, 'user_id' => $this->user_id])
-            ->getSingleScalarResult();
-        $count = (int) $result;
+        $table = Database::get_main_table(TABLE_MAIN_GRADEBOOK_RESULT);
+        $sql = "SELECT COUNT(*) AS count
+                FROM $table gr
+                WHERE gr.evaluation_id = $this->evaluation
+                AND gr.user_id = $this->user_id
+        ";
+        $result = Database::query($sql);
+        $row = Database::fetch_array($result);
+        $count = (int) $row['count'];
 
         return $count > 0;
     }