Can't change preferred apps on Xubuntu 20.04 after upgrade from 18.04

[Tom H]

On Thu, Nov 19, 2020 at 10:06 PM MR ZenWiz <mrzenwiz at gmail.com>
wrote:
>
> I recently upgraded my partner's laptop from Xubuntu 18.04, which
> was running nicely, to 20.04. For the most part it works fine.
>
> However, today I went in to change the preferred web browser from
> Mozilla Firefox to Google Chrome, and the change does not stick,
> or even take hold. It never changes from Firefox. I tried to
> change the mail reader to Chrome also, and hit the same wall.
>
> On my desktop, on which I installed a fresh 20.04, I have no
> trouble changing the preferred apps - I have chrome for both
> browser and reader.
>
> I notice in the preferred apps listing it shows Debian Sensible
> browser and chrome, but both have the "not" slashed circle over
> them inside a black rectangle. I would guess that this is part of
> the problem, but I also tried selecting "Other" and entered the
> FQPN of the Chrome executable (/opt/google/chrome/chrome - I also
> tried google-chrome as the leaf) and that also does not work.
>
> WTH is going on here? What do I have to do to change this setting?
> It "should" be straightforward and just offer me the options among
> what's installed, but that doesn't seem to work.

The file that controls preferred apps is "~/.config/mimeapps.list". Is
it being updated? Does it have the right ownership and mode? Is it
corrupt?