:date: 2020-10-16 ======================== Friday, October 16, 2020 ======================== 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 :file:`/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