Looking below at the output it shows that acme tries to connect to https://files.barlians instead of https://files.barlians.com.
My domain is: files.barlians.com
I ran this command:
letsencrypt certonly -a webroot --webroot-path=/var/www/html/t3-cms-v8.barlians.com -d files.barlians.com
It produced this output:
The following errors were reported by the server:
Domain: files.barlians.com
Type: connection
Detail: Fetching https://files.barlians/.well-known/acme-challenge/311ktTrQMLXfaGy1Y7nvEvg3WNwoVwDLbvBY-iBnWbg: Error getting
validation data
web server: nginx version: nginx/1.10.3 (Ubuntu)
operating system: Ubuntu Linux 16.04.1
using unmanaged VPS
I can login to a root shell on my machine.
Using latest webmin (version 1.870), but it’s not used for updating certificates. certificates I update by ssh-commandline.