Cannot upgrade to Ubuntu 15.10 (Could not calculate the upgrade)

[Jose Gómez]

I have Ubuntu 15.04 installed, with three PPAs enabled (Cinnamon Stable, Oracle Java and Google's tlk plugin).

I tried to upgrade to Ubuntu 15.10, and during the upgrade process I got the "Could not calculate the upgrade" error. Disabling the PPAs didn't help.

Looking into /var/log/dist-upgrade/main.log I saw an error with the package unity. As I use cinnamon as my DM, I just uninstalled unity. But now there is a similar error with update-manager, which I cannot uninstall, as I need that one for the upgrade.

This is the current error shown:

2015-10-26 10:45:12,421 ERROR Dist-upgrade failed: 'The package 'update-manager' is marked for removal but it is in the removal blacklist.'

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: ubuntu-release-upgrader-core 1:15.04.14.2
Uname: Linux 4.0.4-040004-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.5
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: X-Cinnamon
Date: Mon Oct 26 10:45:09 2015
InstallationDate: Installed on 2014-02-15 (617 days ago)
InstallationMedia: Ubuntu-GNOME 14.04 "Trusty Tahr" - Alpha amd64 (20140203)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to vivid on 2015-10-26 (0 days ago)
VarLogDistupgradeTermlog:

[Jose Gómez (adler-dreamcoder)]

Update: I just enabled the vivid-proposed repository, which made some updates available. However, after installing all of them and restarting the system, the problem persists.

[Jose Gómez (adler-dreamcoder)]

After much testing, I ended up uninstalling all the "foreign" packages in /var/log/dist-upgrade/main.log and the update is in progress now. I'd say it was cinnamon what was preventing the upgrade.

[Brian Murray (brian-murray)]

As you've discovered it is not enough to just disable PPAs as the those PPAs may have provided package version numbers greater than the versions in the release to which you are trying to upgrade. This then can cause problems for the release upgrade calculation. For future reference there is a tool called ppa-purge which will disable PPAs and downgrade package versions to those from the official Ubuntu archive.