Piwigo encountered a non recoverable error

[mysql error ] 
mysqlnd cannot connect to MySQL 4.1+ using the old insecure authentication. Please use an administration tool to reset your password with the command SET PASSWORD = PASSWORD('your_existing_password'). This will store a new, and more secure, hash value in mysql.user. If this user is used in other scripts executed by PHP 5.2 or earlier you might need to remove the old-passwords flag from your my.cnf file

#1	my_error /var/home/pries_co.at/www/fotos/include/common.inc.php(124)
#2	include_once /var/home/pries_co.at/www/fotos/comments.php(13)