Iredmail Could not save new password. Encryption function missing

It's a bug of iRedMail, the latest Roundcubemail-1.2.0 changed sample config file of its password plugin, this causes iRedMail didn't correctly configure path of 'doveadm' command. Please fix it by following steps below:

*) Open file /opt/www/roundcubemail/plugins/password/config.inc.php, search parameter name "password_dovecotpw". Like this:

$config['password_dovecotpw'] =

*) You will find duplicate parameters, remove one of them, and make sure the remained one is set to:
$config['password_dovecotpw'] = '/usr/bin/doveadm pw';