[Bug 1923080] Re: ubuntu upgrade to 20 from 18 .04.5 fails. Error message is indeterminate.

[Manfred Hampl]

I assume that the message that you are missing should read

    This was likely caused by:
    Unofficial software packages not provided by Ubuntu
    Please use the tool 'ppa-purge' from the ppa-purge
    package to remove software from a Launchpad PPA and
    try the upgrade again.

This is the case on your system. You have added software from outside
Ubuntu, namely the oibaf PPA.

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https://bugs.launchpad.net/bugs/1923080

Title:
  ubuntu upgrade to 20 from 18 .04.5 fails.  Error message is
  indeterminate.

Status in ubuntu-release-upgrader package in Ubuntu:
  New

Bug description:
  Ubuntu 18.04.5 LTS
  upgrading to latest LTS version.
  Expecting the upgrade to proceed or at least give me a useful error, however it doesn't display an error.  Instead it just states "Could not calculate the upgrade.  An unresolvable problem occurred while calculating the upgrade. If none of this applies report the bug.
  Since there is no problem listed with the error message, I would expect one to be listed.  Since none of the error does apply (nothing listed) I'm reporting it as a bug.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: ubuntu-release-upgrader-core 1:18.04.42
  ProcVersionSignature: Ubuntu 4.15.0-140.144-generic 4.15.18
  Uname: Linux 4.15.0-140-generic x86_64
  NonfreeKernelModules: nvidia_uvm nvidia
  ApportVersion: 2.20.9-0ubuntu7.23
  Architecture: amd64
  CrashDB: ubuntu
  CurrentDesktop: ubuntu:GNOME
  Date: Thu Apr  8 13:50:31 2021
  InstallationDate: Installed on 2017-10-13 (1273 days ago)
  InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
  PackageArchitecture: all
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: ubuntu-release-upgrader
  UpgradeStatus: Upgraded to bionic on 2021-04-08 (0 days ago)
  VarLogDistupgradeTermlog:

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