Clone dropdown is not showing url with https protocol

Hi

I’m using gitlab 11.11.3. When I enter to some project and I see the Clone downdown and it shows ‘Clone with HTTP’ with url http://gitlab.example.com/code/app.git. I wish it shows https://gitlab.example.com/code/app.git. The Home page URL (Sign-in restrictions) is https://gitlab.example.com/users/sign_in. So I tried to change the property external_url from http://gitlab.example.com to https://gitlab.example.com on /etc/gitlab/gitlab.rb file, but I get the following error message:

Running handlers:
There was an error running gitlab-ctl reconfigure:

letsencrypt_certificate[cove.reniec.gob.pe] (letsencrypt::http_authorization line 3) had an error: Acme::Client::Error::Unauthorized: acme_certificate[staging] (/opt/gitlab/embedded/cookbooks/cache/cookbooks/letsencrypt/resources/certificate.rb line 20) had an error: Acme::Client::Error::Unauthorized: Account creation on ACMEv1 is disabled. Please upgrade your ACME client to a version that supports ACMEv2 / RFC 8555. See https://community.letsencrypt.org/t/end-of-life-plan-for-acmev1/88430 for details.

Just it case, on firewall the ports 80 and 443 are enabled.

What can I do?