On Sun, Jun 20, 2021 at 09:51:32AM +0100, Jenny Hopkins wrote:
>
> 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?

I'd try this and remove those packages, do the upgrade and add them back.

https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1898815