Let'sEncrypt with Cloudflare

LE has a weird issue with having locales set on Ubuntu 16.04. Make sure you have them set up. Just run

export LC_ALL="en_US.UTF-8"
export LC_CTYPE="en_US.UTF-8"

or run this

export LC_ALL="C"

If that doesn't work, try the following and run the command again.

locale-gen en_US en_US.UTF-8
dpkg-reconfigure locales

I hope it helps.