BackBox is not an official Ubuntu derivative and you'll need to bring your issue to the attention of the BackBox developers. As far as I know they don't use Launchpad.
** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1603775 Title: can't upgrade backbox-ubuntu 14.04 to 15.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1603775/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs