Warning: mysql_connect(): The server requested authentication method unknown to the client [mysql_old_password] in /www/arena-software.com.ar/htdocs/configuration.php on line 21

Warning: mysql_connect(): The server requested authentication method unknown to the client in /www/arena-software.com.ar/htdocs/configuration.php on line 21
I cannot connect to the database because: The server requested authentication method unknown to the client