Use Certbot Standalone Mode to Retrieve Let's Encrypt SSL Certificates

Hi,

I am following the instructions in the link below [1] to install an SSL certificate for my domain and I get an error:

#sudo certbot certonly --standalone --preferred-challenges http -d example.com
usage: 
  certbot [SUBCOMMAND] [options] [-d DOMAIN] [-d DOMAIN] ...

Certbot can obtain and install HTTPS/TLS/SSL certificates.  By default,
it will attempt to use a webserver both for obtaining and installing the
certificate. 
certbot: error: Unexpected line 0 in /etc/letsencrypt/cli.ini: ≈# Because we are using logrotate for greater flexibility, disable the
root@webstore-mongodb:/var/www# 

What am I doing wrong?

Thanks.

How To Use Certbot Standalone Mode to Retrieve Let’s Encrypt SSL Certificates on Ubuntu 16.04