Warning: mysql_connect(): The server requested authentication method unknown to the client [mysql_old_password] in /home/romeogr/public_html/guestbook3.php on line 3

Warning: mysql_connect(): The server requested authentication method unknown to the client in /home/romeogr/public_html/guestbook3.php on line 3
I cannot connect to the database. Error :The server requested authentication method unknown to the client