I encountered a similar problem when upgrading a container from 13.04 to 13.10.
The problem was that the listed dependencies for ubuntu-release- upgrader-core were not sufficient. The solution was to install python-apt. (Even that was a bit difficult; I had to manually create an empty file, /etc/python2.7/sitecustomize.py). If python-apt doesn't solve the problem, then you could try searching for other missing dependencies. Here's one way to do that: (1) List the reverse-dependencies of ubuntu-release-upgrader-core: apt-cache rdepends ubuntu-release-upgrader-core On ubuntu-14.04 the reverse-dependencies include update-manager-core. (2) List the dependencies of update-manager-core, apt-cache depends update-manager-core Try installing some or all of these dependencies and see whether it solves the problem. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1511875 Title: Can't upgrade from 15.10 Wily to 16.04 Xenial in LXC container To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1511875/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs