I created this Droplet a few months ago. After some time i tried to connect to it again. I got everytime I tried

$ ssh user@server
Permission denied (publickey)

So I just tried to follow the steps again in this tutorial:

https://www.digitalocean.com/community/tutorials/how-to-set-up-ssh-keys--2

But anything that connects to the server with SSH (ssh-copy-id) ends abruptly with "Permission denied (publickey)"

The public key I created last was added in Settings > Security > SSH Keys

Any ideas?