# I know you've got stuck for too long ^_^Y
# Locale is not configured correct. I don't know what broke that. Maybe time did.
# I fixed it on my ubuntu 14 & 16 servers.
# Follow the steps below or run this script on your machine.

# step 1
# ensure this line in `/etc/default/locale` file and `/etc/environment` file
# LANG="en_US.UTF-8"
sudo echo '\nLANG="en_US.UTF-8"' >> /etc/default/locale && /etc/environment

# step 2
sudo locale-gen en_US en_US.UTF-8 && sudo dpkg-reconfigure locales