[Bug 2092462] [NEW] Cannot upgrade from Ubuntu 20.04: "An unresolvable problem occurred"

[herchu]

Public bug reported:

Upgrading from Ubuntu 20.04. The upgrader stops at:

```
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'. 
```

I have already removed all PPAs, uninstalled most manual packages I
found; and there are no 'held back' packages. How can I find what is the
package or dependency that causes upgrader to fail?

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubuntu-release-upgrader-core 1:20.04.41
ProcVersionSignature: Ubuntu 5.15.0-127.137~20.04.1-generic 5.15.168
Uname: Linux 5.15.0-127-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.27
Architecture: amd64
CasperMD5CheckResult: skip
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Tue Dec 24 18:38:35 2024
InstallationDate: Installed on 2020-09-19 (1557 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to focal on 2024-12-24 (0 days ago)

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


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

-- 
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https://bugs.launchpad.net/bugs/2092462

Title:
  Cannot upgrade from Ubuntu 20.04: "An unresolvable problem occurred"

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

Bug description:
  Upgrading from Ubuntu 20.04. The upgrader stops at:

  ```
  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'. 
  ```

  I have already removed all PPAs, uninstalled most manual packages I
  found; and there are no 'held back' packages. How can I find what is
  the package or dependency that causes upgrader to fail?

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: ubuntu-release-upgrader-core 1:20.04.41
  ProcVersionSignature: Ubuntu 5.15.0-127.137~20.04.1-generic 5.15.168
  Uname: Linux 5.15.0-127-generic x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.20.11-0ubuntu27.27
  Architecture: amd64
  CasperMD5CheckResult: skip
  CrashDB: ubuntu
  CurrentDesktop: ubuntu:GNOME
  Date: Tue Dec 24 18:38:35 2024
  InstallationDate: Installed on 2020-09-19 (1557 days ago)
  InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
  PackageArchitecture: all
  SourcePackage: ubuntu-release-upgrader
  UpgradeStatus: Upgraded to focal on 2024-12-24 (0 days ago)

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