Adding a production domain to a test server

[mnordhoff]

You can also upgrade to Certbot 0.21.0 or newer.

I don't know if new packages are available for CentOS yet. If you want to upgrade, you may have to use certbot-auto or another installation method, which comes with its own inconveniences.

Solution: Client with the currently selected authenticator does not support any combination of challenges that will satisfy the CA

I…

@BananaOnAcid

Another question, what if I only create a subdomain : mycustomer.myserver.net ? Right now I get a certificate error with Chrome. Is there an easy way to use myserver.net certificate on all its subdomains ?

You would have to issue a new certificate, with a Certbot command similar to what was used to create the certificate originally. For example, maybe:

sudo certbot --apache --expand -d myserver.net -d www.myserver.net -d mycustomer.myserver.net

Keep the rate limits in mind.

Rate Limits - Let's Encrypt

At the moment, there isn't really another option available. However, Let's Encrypt plans to start offering wildcard certificates February 27. You would have to upgrade Certbot, and use DNS-01 validation, but you could then get a certificate for *.myserver.net.