Requesting root privileges to run with virtualenv: /root/.local/share/letsencrypt/bin/letsencrypt

Hello,
my os is centos7 ,and when i run the command “./letsencrypt-auto”,
it tips : Updating letsencrypt and virtual environment dependencies…
Requesting root privileges to run with virtualenv: /root/.local/share/letsencrypt/bin/letsencrypt
No installers are available on your OS yet; try running “letsencrypt-auto certonly” to get a cert you can install manually

Hi,
run as sudo
#sudo ./letsencrypt-auto — this must work

Thanks,
I run the following command,
sudo ./letsencrypt-auto certonly --standalone --email xxx@gmail.com -d www.on-img.com -d on-img.com
it tips:

    IMPORTANT NOTES:
     - The following errors were reported by the server:

       Domain: on-img.com
       Type:   urn:acme:error:connection
       Detail: Failed to connect to host for DVSNI challenge

       Domain: www.on-img.com
       Type:   urn:acme:error:connection
       Detail: Failed to connect to host for DVSNI challenge

Are the DNS records for those names pointing at the server where you ran the command? Is there another web server running on that server which was active at the time you ran the command?