diff --git a/main/gradebook/gradebook_add_eval.php b/main/gradebook/gradebook_add_eval.php
index 885dccb201..20f194484e 100755
--- a/main/gradebook/gradebook_add_eval.php
+++ b/main/gradebook/gradebook_add_eval.php
@@ -43,7 +43,8 @@ if ($form->validate()) {
 	$eval->add();
 	if ($eval->get_course_code() == null) {
 		if ($values['adduser'] == 1) {
-			header('Location: gradebook_add_user.php?selecteval=' . $eval->get_id());
+            //Disabling code when course code is null see issue #2705
+			//header('Location: gradebook_add_user.php?selecteval=' . $eval->get_id());
 			exit;
 		} else {
 			header('Location: '.Security::remove_XSS($_SESSION['gradebook_dest']).'?selectcat=' . $eval->get_category_id());
diff --git a/main/gradebook/gradebook_add_user.php b/main/gradebook/gradebook_add_user.php
index 57b884f764..fa854bf34f 100755
--- a/main/gradebook/gradebook_add_user.php
+++ b/main/gradebook/gradebook_add_user.php
@@ -2,6 +2,11 @@
 
 /* For licensing terms, see /license.txt */
 
+//Disabling code when course code is null (gradebook as a tab) see issue #2705
+exit;
+
+
+
 $language_file = 'gradebook';
 require_once '../inc/global.inc.php';
 $this_section = SECTION_MYGRADEBOOK;
diff --git a/main/gradebook/lib/be/dropboxlink.class.php b/main/gradebook/lib/be/dropboxlink.class.php
index cc7f867b4b..b56cb1cb5b 100755
--- a/main/gradebook/lib/be/dropboxlink.class.php
+++ b/main/gradebook/lib/be/dropboxlink.class.php
@@ -19,12 +19,16 @@ class DropboxLink extends EvalLink
     }
 
 
-// FUNCTIONS IMPLEMENTING ABSTRACTLINK
+    /**
+     * 
+     * Returns the URL of a document
+     * This funcion is loaded when using a gradebook as a tab (gradebook = -1) see issue #2705
+     */
 
 	public function get_view_url ($stud_id) {
 		// find a file uploaded by the given student,
 		// with the same title as the evaluation name
-
+		
     	$eval = $this->get_evaluation();
 
 		$sql = 'SELECT filename FROM '.$this->get_dropbox_table()
@@ -34,8 +38,9 @@ class DropboxLink extends EvalLink
 		$result = Database::query($sql);
 		if ($fileurl = Database::fetch_row($result)) {
 	    	$course_info = Database :: get_course_info($this->get_course_code());
-			$url = api_get_path(WEB_PATH).'main/gradebook/open_document.php?file='.$course_info['directory'].'/'.$fileurl[0];
-			return $url;
+			//$url = api_get_path(WEB_PATH).'main/gradebook/open_document.php?file='.$course_info['directory'].'/'.$fileurl[0];
+			//return $url;
+            return null;
 		} else {
 			return null;
 		}
diff --git a/main/gradebook/lib/be/studentpublicationlink.class.php b/main/gradebook/lib/be/studentpublicationlink.class.php
index a96d8d9457..97019133a2 100755
--- a/main/gradebook/lib/be/studentpublicationlink.class.php
+++ b/main/gradebook/lib/be/studentpublicationlink.class.php
@@ -21,7 +21,12 @@ class StudentPublicationLink extends AbstractLink
     }
 
 
-    // FUNCTIONS IMPLEMENTING ABSTRACTLINK
+    /**
+     * 
+     * Returns the URL of a document
+     * This funcion is loaded when using a gradebook as a tab (gradebook = -1), see issue #2705
+     * 
+     */
 
 	public function get_view_url ($stud_id) {
 		// find a file uploaded by the given student,
@@ -39,8 +44,9 @@ class StudentPublicationLink extends AbstractLink
 		$result = Database::query($sql);
 		if ($fileurl = Database::fetch_row($result)) {
 	    	$course_info = Database :: get_course_info($this->get_course_code());
-			$url = api_get_path(WEB_PATH).'main/gradebook/open_document.php?file='.$course_info['directory'].'/'.$fileurl[0];
-			return $url;
+			//$url = api_get_path(WEB_PATH).'main/gradebook/open_document.php?file='.$course_info['directory'].'/'.$fileurl[0];
+			//return $url;
+            return null;
 		 } else {
 			return null;
 		}
diff --git a/main/gradebook/lib/fe/displaygradebook.php b/main/gradebook/lib/fe/displaygradebook.php
index 5bdc857685..ce13c96eee 100755
--- a/main/gradebook/lib/fe/displaygradebook.php
+++ b/main/gradebook/lib/fe/displaygradebook.php
@@ -15,9 +15,9 @@ class DisplayGradebook
 			$header = '<div class="actions">';
 			$header .= '<a href="'.Security::remove_XSS($_SESSION['gradebook_dest']).'?selectcat=' . $selectcat . '">'. Display::return_icon(('back.png'),get_lang('FolderView')) . get_lang('FolderView') . '</a>';
 			if ($evalobj->get_course_code() == null) {
-				$header .= '<a href="gradebook_add_user.php?selecteval=' . $evalobj->get_id() . '"><img src="../img/add_user_big.gif" alt="' . get_lang('AddStudent') . '" align="absmiddle" /> ' . get_lang('AddStudent') . '</a>';
-			}
-			elseif (!$evalobj->has_results()) {
+                //Disabling code when course code is null see issue #2705
+				//$header .= '<a href="gradebook_add_user.php?selecteval=' . $evalobj->get_id() . '"><img src="../img/add_user_big.gif" alt="' . get_lang('AddStudent') . '" align="absmiddle" /> ' . get_lang('AddStudent') . '</a>';
+			} elseif (!$evalobj->has_results()) {
 				$header .= '<a href="gradebook_add_result.php?selectcat=' . $selectcat . '&selecteval=' . $evalobj->get_id() . '"><img src="../img/filenew.gif" alt="' . get_lang('AddResult') . '" align="absmiddle"/> ' . get_lang('AddResult') . '</a>';
 			}
 			$header .= '<a href="' . api_get_self() . '?&selecteval=' . $evalobj->get_id() . '&import="><img src="../img/import_data.gif" border="0" alt="" />' . ' ' . get_lang('ImportResult') . '</a>';
diff --git a/main/gradebook/open_document.php b/main/gradebook/open_document.php
index cff9ffe900..86451f15e5 100755
--- a/main/gradebook/open_document.php
+++ b/main/gradebook/open_document.php
@@ -1,7 +1,11 @@
 <?php
 /* For licensing terms, see /license.txt */
+//Disabling code due issue #2705 gradebook with id "-1" 
+exit;
+/*
 require_once '../inc/global.inc.php';
 require_once '../inc/lib/document.lib.php';
 api_block_anonymous_users();
 DocumentManager :: file_send_for_download(api_get_path(SYS_COURSE_PATH).$_GET['file']);
-exit;
\ No newline at end of file
+exit;
+*/
\ No newline at end of file