Fatal error: Uncaught Error: Undefined constant "BASE_URL" in /var/www/html/whatsapp-sender/config/helpers.php:3 Stack trace: #0 /var/www/html/whatsapp-sender/actions/set_preferences.php(31): redirect('login.php') #1 {main} thrown in /var/www/html/whatsapp-sender/config/helpers.php on line 3