I’m using Debian 7 (wheezy).
Yes, I’m using nginx as you mentioned)
I’v tried manual
./letsencrypt-auto --agree-dev-preview --server \https://acme-v01.api.letsencrypt.org/directory -a manual auth
and standalone
/etc/init.d/nginx stop
./letsencrypt-auto certonly --standalone --email myemail@gmail.com -d replyme.ru
Both times I haven’t got any errors and got message that I should make secure backup of “/etc/letsencrypt”