diff --git a/main/inc/lib/course.lib.php b/main/inc/lib/course.lib.php
index 6a71bed002..fa879b0b41 100755
--- a/main/inc/lib/course.lib.php
+++ b/main/inc/lib/course.lib.php
@@ -751,7 +751,8 @@ class CourseManager
         $status = STUDENT,
         $sessionId = 0,
         $userCourseCategoryId = 0,
-        $checkTeacherPermission = true
+        $checkTeacherPermission = true,
+        $displayFlashMessages = true
     ) {
         $userId = (int) $userId;
         $status = (int) $status;
@@ -763,7 +764,9 @@ class CourseManager
         $courseInfo = api_get_course_info($courseCode);
 
         if (empty($courseInfo)) {
-            Display::addFlash(Display::return_message(get_lang('CourseDoesNotExist'), 'warning'));
+            if ($displayFlashMessages) {
+                Display::addFlash(Display::return_message(get_lang('CourseDoesNotExist'), 'warning'));
+            }
 
             return false;
         }
@@ -771,7 +774,9 @@ class CourseManager
         $userInfo = api_get_user_info($userId);
 
         if (empty($userInfo)) {
-            Display::addFlash(Display::return_message(get_lang('UserDoesNotExist'), 'warning'));
+            if ($displayFlashMessages) {
+                Display::addFlash(Display::return_message(get_lang('UserDoesNotExist'), 'warning'));
+            }
 
             return false;
         }
@@ -798,7 +803,9 @@ class CourseManager
                         c_id = $courseId
                     ";
             if (Database::num_rows(Database::query($sql)) > 0) {
-                Display::addFlash(Display::return_message(get_lang('AlreadyRegisteredToCourse'), 'warning'));
+                if ($displayFlashMessages) {
+                    Display::addFlash(Display::return_message(get_lang('AlreadyRegisteredToCourse'), 'warning'));
+                }
 
                 return false;
             }
@@ -806,7 +813,9 @@ class CourseManager
             if ($checkTeacherPermission && !api_is_course_admin()) {
                 // Check in advance whether subscription is allowed or not for this course.
                 if ((int) $courseInfo['subscribe'] === SUBSCRIBE_NOT_ALLOWED) {
-                    Display::addFlash(Display::return_message(get_lang('SubscriptionNotAllowed'), 'warning'));
+                    if ($displayFlashMessages) {
+                        Display::addFlash(Display::return_message(get_lang('SubscriptionNotAllowed'), 'warning'));
+                    }
 
                     return false;
                 }
@@ -835,7 +844,10 @@ class CourseManager
                         );
 
                         if ($count >= $maxStudents) {
-                            Display::addFlash(Display::return_message(get_lang('MaxNumberSubscribedStudentsReached'), 'warning'));
+                            if ($displayFlashMessages) {
+                                Display::addFlash(Display::return_message(get_lang('MaxNumberSubscribedStudentsReached'),
+                                    'warning'));
+                            }
 
                             return false;
                         }
@@ -851,15 +863,17 @@ class CourseManager
                 ['status' => $status, 'sort' => $maxSort, 'user_course_cat' => $userCourseCategoryId]
             );
 
-            Display::addFlash(
-                Display::return_message(
-                    sprintf(
-                        get_lang('UserXAddedToCourseX'),
-                        $userInfo['complete_name_with_username'],
-                        $courseInfo['title']
+            if ($displayFlashMessages) {
+                Display::addFlash(
+                    Display::return_message(
+                        sprintf(
+                            get_lang('UserXAddedToCourseX'),
+                            $userInfo['complete_name_with_username'],
+                            $courseInfo['title']
+                        )
                     )
-                )
-            );
+                );
+            }
 
             $send = api_get_course_setting('email_alert_to_teacher_on_new_user_in_course', $courseInfo);
 
diff --git a/main/inc/lib/usergroup.lib.php b/main/inc/lib/usergroup.lib.php
index 38550e0973..e1235d07b1 100755
--- a/main/inc/lib/usergroup.lib.php
+++ b/main/inc/lib/usergroup.lib.php
@@ -1032,10 +1032,28 @@ class UserGroup extends Model
                 if ($course_info) {
                     if (!empty($user_list)) {
                         foreach ($user_list as $user_id) {
-                            CourseManager::subscribeUser(
+                            $subscribed = CourseManager::subscribeUser(
                                 $user_id,
-                                $course_info['code']
+                                $course_info['code'],
+                                STUDENT,
+                                0,
+                                0,
+                                true,
+                                false
                             );
+                            if (!$subscribed) {
+                                $userInfo = api_get_user_info($user_id);
+                                Display::addFlash(
+                                    Display::return_message(
+                                        sprintf(
+                                            get_lang('UserXNotSubscribedToCourseX'),
+                                            $userInfo['complete_name_with_username'],
+                                            $course_info['title']
+                                        ),
+                                        'error'
+                                    )
+                                );
+                            }
                         }
                     }
                     $params = [
@@ -1210,7 +1228,28 @@ class UserGroup extends Model
                 if (!empty($course_list)) {
                     foreach ($course_list as $course_id) {
                         $course_info = api_get_course_info_by_id($course_id);
-                        CourseManager::subscribeUser($user_id, $course_info['code']);
+                        $subscribed = CourseManager::subscribeUser(
+                            $user_id,
+                            $course_info['code'],
+                            STUDENT,
+                            0,
+                            0,
+                            true,
+                            false
+                        );
+                        if (!$subscribed) {
+                            $userInfo = api_get_user_info($user_id);
+                            Display::addFlash(
+                                Display::return_message(
+                                    sprintf(
+                                        get_lang('UserXNotSubscribedToCourseX'),
+                                        $userInfo['complete_name_with_username'],
+                                        $course_info['title']
+                                    ),
+                                    'error'
+                                )
+                            );
+                        }
                     }
                 }
                 $params = [