Update for UbuntuMATE 16.04.6 broke the GUI

[Colin Law]

On Tue, 20 Aug 2019 at 22:27, Bret Busby <bret.busby at gmail.com> wrote:
>
> Hello.
>
> A few hours ago, I performed a system update on one of my UbuntuMATE
> 16.04.6 systems, and it has broken the system.
>
> The panel in the GUI is broken, and the taskbar has been eliminated,
> by the update, rendering the GUI unusable.
>
> Is it possible to reverse the system update?

What do you mean by 'system update'?

What does this show
sudo apt-get update && sudo apt-get dist-upgrade

Colin