Certbot / letsencrypt got jessie-backports is invalid

Environment

Debain 8.4 , 32bit

Install certbot / letsencrypt

apt-get install letsencrypt -t jessie-backports

Got error message

Reading package lists... Done
E: The value 'jessie-backports' is invalid for APT::Default-Release as such a release is not available in the sources

Fix it by add following line

vim /etc/apt/sources.list

    deb http://http.debian.net/debian jessie-backports main

Update and Upgrade it

apt-get update
apt-get upgrade

Refernece

• https://rubenerd.com/debian-wheezy-backports/