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The message -- 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. .. --- looks like it applies. A quick scan of your sources and I can see four different releases for packages (12.04, 17.10, 18.04, 19.04) so you should first remove the Unofficial software packages not provided by Ubuntu (PPA's are 3rd party sources not provided by Ubuntu) then try again. I've marked this as incomplete because unofficial sources are still there. If you believe I am in error, please return this the status to new and leave a comment as to why. ** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1840386 Title: impossible calculate upgrade of version To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1840386/+subscriptions -- ubuntu-bugs mailing list firstname.lastname@example.org https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs