Is it possible to secure domain with no hosting using Lets Encrypt SSL certificate in Plesk?

Question

Is it possible to secure domain without hosting using Lets Encrypt SSL certificate in Plesk?

Answer

It's not possible to use Lets Encrypt for domains without hosting. When Let's Encrypt certificate is installed/updated for domain, it places temporary files to  /example.com/httpdocs/.well-known folder. Since httpdocs folder doesn't exist for domains without hosting, it's not possible to place the temporary files.

To install Let's Encrypt certificate for a domain without hosting, enable hosting first by following the steps below:

1. Log into Plesk
2. Go to Domains > example.com > Hosting Settings
3. Change and select Website hosting and click OK or Apply at the bottom of the page
4. Issue the new Lets Encrypt SSL certificate 

Also see:
Is it possible to secure webmail in Plesk on domain without web hosting with an SSL certificate?