[Bug 1781412] Re: do-release-upgrade crashed with UnboundLocalError in _replaceDebsWithSnaps(): local variable 'proc' referenced before assignment

[Launchpad Bug Tracker]

This bug was fixed in the package ubuntu-release-upgrader - 1:18.04.21

---------------
ubuntu-release-upgrader (1:18.04.21) bionic; urgency=medium

  * DistUpgradeQuirks.py: when a snap fails to install try the next one
    instead of trying to check the return code of the called process which
    causes a Traceback. (LP: #1781412)
  * data/mirrors.cfg: Update the list of official mirrors.

ubuntu-release-upgrader (1:18.04.20) bionic; urgency=medium

  * Purge obsolete packages, if user agrees to remove obsolete
    packages. LP: #1775660
  * DistUpgradeQuirks.py, DistUpgradeController.py: move inhibiting of
    gnome-session idle so that it is called immediately after the upgrade
    starts (LP: #1778817), present a dialog notifying that the lock screen has
    been disabled (LP: #1174093), and do not reenable the lock screen as it
    may fail to work after a release upgrade. (LP: #1780342)
  * DistUpgradeQuirks.py: Add in a quirk for upgrading to Bionic that will
    check if the system has connectivity to the snap store and replace some
    desktop packages with snaps to ensure the system is similar to a fresh
    install. (LP: #1780841)
  * data/mirrors.cfg: Update the list of official mirrors.

 -- Brian Murray <brian at ubuntu.com>  Sun, 15 Jul 2018 10:16:16 -0700

** Changed in: ubuntu-release-upgrader (Ubuntu Bionic)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1781412

Title:
  do-release-upgrade crashed with UnboundLocalError in
  _replaceDebsWithSnaps(): local variable 'proc' referenced before
  assignment

Status in ubuntu-release-upgrader package in Ubuntu:
  Fix Released
Status in ubuntu-release-upgrader source package in Bionic:
  Fix Released

Bug description:
  Adding support for transitioning debs to snaps when upgrading from
  16.04 to 18.04, bug 1780841, ended up creating a crash in a specific
  scenario.

  [Test Case]
  1) Install and Ubuntu 16.04 desktop system
  2) Modify /etc/hosts so api.snapcraft.io resolves to 127.0.0.1
  3) Upgrade to Ubuntu 18.04 using u-r-u 18.04.20 (sudo ./bionic --frontend DistUpgradeViewText)
  4) Observe the Traceback in this bug report

  N.B. You'll need to manually download and extract the release upgrader
  tarball from http://archive.ubuntu.com/ubuntu/dists/bionic-
  proposed/main/dist-upgrader-all/current/ since the upgrade is to the
  development and proposed release.

  I was testing a release upgrade from Ubuntu 16.04 to Ubuntu 18.04
  where I had no connectivity to the snap store and encountered this
  crash.

  ProblemType: CrashDistroRelease: Ubuntu 18.04
  Package: ubuntu-release-upgrader-core 1:18.04.20
  ProcVersionSignature: Ubuntu 4.4.0-121.145-generic 4.4.117
  Uname: Linux 4.4.0-121-generic x86_64
  ApportVersion: 2.20.9-0ubuntu7.2
  Architecture: amd64
  CrashDB: ubuntu
  Date: Wed Jul 11 20:03:49 2018
  ExecutablePath: /usr/bin/do-release-upgrade
  ExecutableTimestamp: 1531169948
  InstallationDate: Installed on 2016-10-04 (645 days ago)
  InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
  InterpreterPath: /usr/bin/python3.5
  PackageArchitecture: all
  ProcCmdline: /usr/bin/python3 ./bionic --frontend DistUpgradeViewText
  ProcCwd: /tmp/u-r-u
  ProcEnviron:
   TERM=screen
   SHELL=/bin/bash
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   LC_CTYPE=en_US.UTF-8
  Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3ubuntu1
  PythonArgs: ['/usr/bin/do-release-upgrade', '--frontend', 'DistUpgradeViewText']
  PythonDetails: /usr/bin/python2.7, Python 2.7.15rc1, python-minimal, 2.7.15~rc1-1SourcePackage: ubuntu-release-upgrader
  Title: do-release-upgrade crashed with UnboundLocalError in _replaceDebsWithSnaps(): local variable 'proc' referenced before assignment
  UpgradeStatus: Upgraded to bionic on 2018-07-12 (0 days ago)
  UserGroups:

  modified.conffile..etc.update-manager.release-upgrades: [modified]
  mtime.conffile..etc.update-manager.release-upgrades: 2016-10-04T13:43:38.934395

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