Can't upgrade from 15.10 Wily to 16.04 Xenial in LXC container

[MegaBrutal]

When I try to upgrade from 15.10 Wily to 16.04 Xenial (actual development version) within an LXC container, the upgrade script hangs at the message „Calculating the changes”.

Steps to reproduce:
1. Make an LXC container with Wily (quickest option is to use lxc-create -t download, choose ubuntu, wily, amd64/i386).
2. Boot up the container, log in, „apt-get -y install ubuntu-release-upgrader-core”.
3. Start the upgrade with „do-release-upgrade -d”.

You will see that the upgrade process will hang at the message „Calculating the changes”.

The process which hangs: „/usr/bin/python3 /tmp/ubuntu-release-upgrader-1mpotr5d/xenial --mode=server --frontend=DistUpgradeViewText --devel-release”

With strace, it is revealed that the process hangs at a „futex” system call:
futex(0x7f4190000c10, FUTEX_WAIT_PRIVATE, 0, NULL

This system call never returns, the process must be interrupted with CTRL-C or kill.

Upgrading to any previous release within an LXC container works without problems, therefore I consider it as a regression.

[oleg (overlayfs)]

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.

[Serge Hallyn (serge-hallyn)]

same thing happens with vivid->wily upgrade.

[Serge Hallyn (serge-hallyn)]

It does this in an unprivileged (true root) as well as a apparmor-unconfined container.

[Marcus Bointon (marcus-synchromedia)]

I'm seeing this in Vivid -> Wily too, but in a Xen VM, not an LXC container. None of the above suggestions worked, it logs the same errors as Serge.

[Christopher (soft-kristal)]

I tried to upgrade to 16.04 RC1 running Ubuntu Gnome 15.10 and get error messages that the update manager exited with an unspecified code. Even the bug report choked when trying to report the issue.

[Jon Brase (jonathan-brase)]

I'm running into the same thing trying to upgrade from 14.04 to 16.04.

After Googling around about the issue, this link at first looked like a promising lead, as I'm running into this on Haswell hardware and I have Core2 hardware that was unaffected:

https://groups.google.com/forum/#!topic/mechanical-sympathy/QbmpZxp6C64

So I tried using a custom-compiled 4.4 series kernel to see if that resolved the issue, and it does cause the upgrade to stop hanging in the futex wait channel, but, unfortunately, does not cause the upgrade to stop hanging. On the 4.4 kernel, system monitor shows the process to be in waiting channel 0 instead of the futex wait channel, but gdb shows the process to be hung in "sem_wait()".

I am running into this on bare hardware, not a container or VM.

Given that I'm seeing it on a Haswell machine but my Core2 laptop did not experience the hang, and given that using a newer kernel version changed the specifics of how the hang is occuring, it seems to be related to the kernel bug discussed at the Google Groups link above, but the kernel bug can't be the whole story, or else the new kernel would have fixed it.

[Jon Brase (jonathan-brase)]

As an update to my comment above, while the release upgrader hung and did not finish the upgrade, it *did* disable all my ppa's and switch over to the Xenial repositories, which ended up leaving my system broken next time I tried pulling in updates (thinking the upgrade had failed completely and the system was still using Trusty repositories). I'm not sure what packages are at Xenial versions and what packages are at still at Trusty versions, there seems to be a mix.

So it seems I can't expect Ubuntu to upgrade between LTS versions without barfing all over itself. Gee, what fun.