If you are still running jessie you probably noticed that the jessie-updates and jessie-backports suites have been removed from mirrors, because you got those error messages: W: Failed to fetch http://ftp.debian.org/debian/dists/jessie-updates/main/binary-amd64/Packages 404 Not Found [IP: 130.89.148.12 80] W: Failed to fetch http://ftp.debian.org/debian/dists/jessie-backports/main/binary-amd64/Pac