[Bug 1899212] [NEW] Upgrade from Ubuntu 18.04.5 LTS to Ubuntu 20.04.1 LTS failed - unresolvable problem

[Vladimir Petrov]

Public bug reported:

I used the default GUI software updater which suggested me to update to
Ubuntu 20. Then the following error was shown:

---
Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade.

 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.

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'.
---

The following command did not produce any output:
sudo grep -i ppa.launchpad.net /etc/apt/sources.list.d/*.list

I read the logs in '/var/log/dist-upgrade' but couldn't find anything
useful.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.38
ProcVersionSignature: Ubuntu 5.4.0-48.52~18.04.1-generic 5.4.60
Uname: Linux 5.4.0-48-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.18
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Fri Oct  9 22:26:24 2020
InstallationDate: Installed on 2020-02-23 (229 days ago)
InstallationMedia: Ubuntu 18.04.4 LTS "Bionic Beaver" - Release amd64 (20200203.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-10-09 (0 days ago)
VarLogDistupgradeTermlog:

** Affects: ubuntu-release-upgrader (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug bionic dist-upgrade

** Summary changed:

- Upgrade from Ubuntu 18.04.5 LTS  to Ubuntu 20.04.1 LTS
+ Upgrade from Ubuntu 18.04.5 LTS  to Ubuntu 20.04.1 LTS failed - unresolvable problem

-- 
You received this bug notification because you are a member of Ubuntu
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Ubuntu.
https://bugs.launchpad.net/bugs/1899212

Title:
  Upgrade from Ubuntu 18.04.5 LTS  to Ubuntu 20.04.1 LTS failed -
  unresolvable problem

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

Bug description:
  I used the default GUI software updater which suggested me to update
  to Ubuntu 20. Then the following error was shown:

  ---
  Could not calculate the upgrade

  An unresolvable problem occurred while calculating the upgrade.

   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.

  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'.
  ---

  The following command did not produce any output:
  sudo grep -i ppa.launchpad.net /etc/apt/sources.list.d/*.list

  I read the logs in '/var/log/dist-upgrade' but couldn't find anything
  useful.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: ubuntu-release-upgrader-core 1:18.04.38
  ProcVersionSignature: Ubuntu 5.4.0-48.52~18.04.1-generic 5.4.60
  Uname: Linux 5.4.0-48-generic x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.20.9-0ubuntu7.18
  Architecture: amd64
  CrashDB: ubuntu
  CurrentDesktop: ubuntu:GNOME
  Date: Fri Oct  9 22:26:24 2020
  InstallationDate: Installed on 2020-02-23 (229 days ago)
  InstallationMedia: Ubuntu 18.04.4 LTS "Bionic Beaver" - Release amd64 (20200203.1)
  PackageArchitecture: all
  SourcePackage: ubuntu-release-upgrader
  UpgradeStatus: Upgraded to bionic on 2020-10-09 (0 days ago)
  VarLogDistupgradeTermlog:

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