[Bug 1924951] Re: Cannot upgrade from 18.04 to 20.04 "An unresolvable problem occured while calculating the upgrade."

[Jochen Ehnes]

Are you talking about this question (see copy of the output in the
terminal below)?


Reading cache

Checking package manager

Continue running under SSH?

This session appears to be running under ssh. It is not recommended 
to perform a upgrade over ssh currently because in case of failure it 
is harder to recover. 

If you continue, an additional ssh daemon will be started at port 
'1022'. 
Do you want to continue? 

Continue [yN]


At this time I press N to stop. 

However, this comes very early in my experience and the result is the
same with and without the -p option. Last time I tried to upgrade the
machine directly I also remember more stuff coming out in the terminal
before the error occured.

Or is there another point later at which you can choose to upgrade or
abort?

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https://bugs.launchpad.net/bugs/1924951

Title:
  Cannot upgrade from 18.04 to 20.04 "An unresolvable problem occured
  while calculating the upgrade."

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

Bug description:
  Description:	Ubuntu 18.04.5 LTS
  Release:	18.04

  I clicked the button to upgrade the system in the dialogue box that
  popped up telling me that there is a new version of the OS I can
  upgrade to.

  After the Distribution upgrade was running for a short while, it
  showed the following error message:

  Could not calculate the upgrade

  An unresolvable problem occurred while calculating the upgrade.

   If none of this applies, then please report this bug using the
  command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal. If
  you want to investigate this yourself the log files in '/var/log/dist-
  upgrade' will contain details about the upgrade. Specifically, look at
  'main.log' and 'apt.log'.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: ubuntu-release-upgrader-core 1:18.04.42
  ProcVersionSignature: Ubuntu 5.4.0-62.70~18.04.1-generic 5.4.78
  Uname: Linux 5.4.0-62-generic x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.20.9-0ubuntu7.21
  Architecture: amd64
  CrashDB: ubuntu
  CurrentDesktop: ubuntu:GNOME
  Date: Mon Apr 19 10:28:34 2021
  InstallationDate: Installed on 2019-09-17 (579 days ago)
  InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
  PackageArchitecture: all
  SourcePackage: ubuntu-release-upgrader
  UpgradeStatus: Upgraded to bionic on 2021-04-19 (0 days ago)
  VarLogDistupgradeTermlog:

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