For fix :
- http://ftp.debian.org/debian jessie-backports/main amd64 Packages 404 Not Found [IP: 130.89.148.12 80]
On Debian 9 : comment jessie-backports in /etc/apt/sources.list.d/backports.list or in /etc/apt/sources.list
For fix :
On Debian 9 : comment jessie-backports in /etc/apt/sources.list.d/backports.list or in /etc/apt/sources.list