We've been hitting the rate limits on autossl so some certificates are expiring instead of automatically renewing. I recommend http://wiki.helionet.org/Installing_a_Let%27s_Encrypt_SSL_Certificate to get your https working again without errors.
You can download your backup at https://www.heliohost.org/backup/ and recreate your account at https://www.heliohost.org/signup/ Let us know if you need help restoring your backup.