Today I ran also in this problem and email_ftp_password_change=1 was already in the directadmin.conf file. I solved it by changing the Roundcube configuration file /var/www/html/roundcube/plugins/password/config.inc.php:
Change this line:
$config[‘password_directadmin_host'] = ‘tcp://localhost';
$config[‘password_directadmin_host'] = ‘ssl://localhost';
in the DirectAdmin driver options. This solved it for me. I just have to keep an eye to it that the next update doesn't overwrite this change.
I just mention this here for if somebody also encounters this issue.