#Error from /var/log/auth.log upon ssh login when ssh key is not accepted:
userauth_pubkey: key type ssh-dss not in PubkeyAcceptedKeyTypes [preauth]

sudo nano /etc/ssh/sshd_config
#add this line
PubkeyAcceptedKeyTypes=+ssh-dss
#save and close
#reload service
sudo service sshd reload