ERROR_LOG
After you set display_errors = Off in php.ini, the error message began to go background. You might want to know where the error message will go.
If you have never set error_log in php.ini explicitly, then the error message goes with the service httpd, which is at:
/var/log/httpd/error_log
If visitors connect the website over SSL, the error message will go to:
/var/log/httpd/ssl_error_log