[Bug 1511875] Re: Can't upgrade from 15.10 Wily to 16.04 Xenial in LXC container

[Christopher]

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.

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https://bugs.launchpad.net/bugs/1511875

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

Status in lxc package in Ubuntu:
  Invalid
Status in ubuntu-release-upgrader package in Ubuntu:
  Triaged

Bug description:
  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.

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