Error when installing


I create my server on Ubuntu Server 18.04. I have install Gitlab locally with that tutorial:

I want to use an external nginx to get a home page.

Here is the configuration file I use:

external_url ''
letsencrypt['enable'] = true
letsencrypt['contact_emails'] = [''] # optional
nginx['redirect_http_to_https_port'] = 80
nginx['redirect_http_to_https'] = true
nginx['enable'] = false
web_server['external_users'] = ['www-data']

When I run the gitllab reconfiguration I get that error:
There was an error running gitlab-ctl reconfigure:

letsencrypt_certificate[] (letsencrypt::http_authorization line 3) had an error: RuntimeError: acme_certificate[staging] (/opt/gitlab/embedded/cookbooks/cache/cookbooks/letsencrypt/resources/certificate.rb line 20) had an error: RuntimeError: [] Validation failed for domain

I notice that the problem has been many time on that forum. I try all the proposed solutions but I still have the problem.