Can't install w/ SSL Docker: "Requested domain ./bitwarden.sh is not a FQDN"

I successfully installed a self-hosted Bitwarden using docker on Ubuntu 16.04 VPS two days ago. Now I’m going insane. Every time I try, using a new domain and VPS, to run the installation, after I select the domain and confirm the Let’s Encrypt certificates request, certbot halts everything with the following error.

"Requested domain ./bitwarden.sh is not a FQDN because it contains an empty label.

Tried different users, domains, VPS, nothing. Can’t install it again… Also googling it doesn’t seem to get me to any useful results.

Help!!!

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