root@data:~# omv-release-upgrade
Upgrading system to 4.0 (Arrakis) ...
Ign file:  InRelease
Ign file:  Release.gpg
Ign file:  Release
Hit http://packages.openmediavault.org arrakis InRelease
Ign file:  Translation-en
Ign file:  Translation-de
Hit http://packages.openmediavault.org arrakis/main amd64 Packages
Ign http://packages.openmediavault.org arrakis/main Translation-en
Ign http://packages.openmediavault.org arrakis/main Translation-de
Ign http://httpredir.debian.org jessie-backports InRelease
Ign http://httpredir.debian.org jessie-backports Release.gpg
Ign http://httpredir.debian.org jessie-backports Release
Ign http://deb.debian.org oldstable InRelease
Hit http://deb.debian.org oldstable Release.gpg
Hit http://deb.debian.org oldstable Release
Hit http://deb.debian.org oldstable/main Sources
Hit http://deb.debian.org oldstable/contrib Sources
Err http://httpredir.debian.org jessie-backports/main amd64 Packages

Err http://httpredir.debian.org jessie-backports/contrib amd64 Packages

Hit http://deb.debian.org oldstable/non-free Sources
Hit http://deb.debian.org oldstable/main amd64 Packages
Err http://httpredir.debian.org jessie-backports/non-free amd64 Packages

Hit http://deb.debian.org oldstable/contrib amd64 Packages
Hit http://deb.debian.org oldstable/non-free amd64 Packages
Hit http://deb.debian.org oldstable/contrib Translation-en
Hit http://deb.debian.org oldstable/main Translation-en
Err http://httpredir.debian.org jessie-backports/contrib amd64 Packages

Hit http://deb.debian.org oldstable/main Translation-de
Hit http://deb.debian.org oldstable/non-free Translation-en
Err http://httpredir.debian.org jessie-backports/non-free amd64 Packages

Err http://httpredir.debian.org jessie-backports/main amd64 Packages
  404  Not Found
Err http://httpredir.debian.org jessie-backports/contrib amd64 Packages
  404  Not Found
Err http://httpredir.debian.org jessie-backports/non-free amd64 Packages
  404  Not Found
Ign http://httpredir.debian.org jessie-backports/contrib Translation-en
Ign http://httpredir.debian.org jessie-backports/contrib Translation-de
Ign http://httpredir.debian.org jessie-backports/main Translation-en
Ign http://httpredir.debian.org jessie-backports/main Translation-de
Ign http://httpredir.debian.org jessie-backports/non-free Translation-en
Ign http://httpredir.debian.org jessie-backports/non-free Translation-de
W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-backports/main/binary-amd64/Packages  404  Not Found

W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-backports/contrib/binary-amd64/Packages  404  Not Found

W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-backports/non-free/binary-amd64/Packages  404  Not Found

E: Some index files failed to download. They have been ignored, or old ones used instead.
root@data:~#