Friday, October 16, 2020ΒΆ

I tried a system upgrade, but it failed:

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'.

Restoring original system state.

Indeed I have some additional ppa files in my /etc/apt/sources.list.d:

$ grep -e '^deb .*http.*' *.list
eid.list:deb http://files.eid.belgium.be/debian bionic main
eid.list:deb http://files2.eid.belgium.be/debian bionic main
gezakovacs-ubuntu-ppa-bionic.list:deb http://ppa.launchpad.net/gezakovacs/ppa/ubuntu bionic main
graphics-tuxedo.list:deb http://graphics.tuxedocomputers.com/ubuntu bionic main
libreoffice-ubuntu-ppa-bionic.list:deb http://ppa.launchpad.net/libreoffice/ppa/ubuntu bionic main
oibaf-tuxedo.list:deb http://oibaf.tuxedocomputers.com/ubuntu bionic main
ria-repository.list:deb https://installer.id.ee/media/ubuntu/ bionic main
riot-im.list:deb [signed-by=/usr/share/keyrings/riot-im-archive-keyring.gpg] https://packages.riot.im/debian/ bionic main
skype-stable.list:deb [arch=amd64] https://repo.skype.com/deb stable main
teamviewer.list:deb http://linux.teamviewer.com/deb stable main
tuxedo-computers.list:deb http://deb.tuxedocomputers.com/ubuntu bionic main
vscode.list:deb [arch=amd64 signed-by=/usr/share/keyrings/packages.microsoft.gpg] https://packages.microsoft.com/repos/vscode stable main