Enable error login in PHP:
ini_set('display_errors', 'on'); ini_set('log_errors', 'on'); ini_set('display_startup_errors', 'on'); ini_set('error_reporting', E_ALL);
Enable Osclass error log (file):
define('OSC_DEBUG', true);
Enable Osclass error log (database queries):
define('OSC_DEBUG_DB', true);
Both should be added into config.php file located in root folder of installation.