Hi folks,

I'm attempting to upgrade from Ubuntu 18.04 -> 20.04.

The 18.04 has been brought completely up to date, and has no broken packages.  However, when I run " sudo do-release-upgrade -d", the system starts preparing for the upgrade then bails out. 

The log file shows:

2021-06-20 09:39:31,393 DEBUG Marking 'ubuntu-desktop' for upgrade
2021-06-20 09:39:31,850 DEBUG Marking 'xubuntu-core' for upgrade
2021-06-20 09:39:32,694 WARNING Can't mark 'xubuntu-core' for upgrade (E:Unable to correct problems, you have held broken packages.)
2021-06-20 09:39:32,694 DEBUG Marking 'xubuntu-desktop' for upgrade
2021-06-20 09:39:33,631 WARNING Can't mark 'xubuntu-desktop' for upgrade (E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.)
2021-06-20 09:39:33,632 DEBUG Marking 'ubuntu-mate-core' for upgrade
2021-06-20 09:39:34,559 WARNING Can't mark 'ubuntu-mate-core' for upgrade (E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.)
2021-06-20 09:39:34,561 DEBUG Marking 'ubuntu-mate-desktop' for upgrade
2021-06-20 09:39:35,491 WARNING Can't mark 'ubuntu-mate-desktop' for upgrade (E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.)
2021-06-20 09:39:39,951 ERROR Dist-upgrade failed: 'Broken packages after upgrade: xubuntu-core, xubuntu-desktop'
2021-06-20 09:39:39,952 DEBUG abort called

However, I don't have any broken packages - both the graphic packages manager and CLI searches confirm this.

Trying to run the upgrade from the GUI just crashes.  Can I do this the debian way, and alter the sources file and do the upgrade that way?

Many thanks,

Jenny