Thunderbird on 20.10 is broken

[Peter Flynn]

On 27/10/2020 14:36, Bret Busby wrote:
> Hello.
> 
> I do not know whether the package maintainer(s) for Thunderbird for
> Ubuntu, subscribe to this list, but, Thunderbird on UbuntuMATE 20.10
> does not load, but instead, displays an error message;
> 
> "
> XML Parsing Error: undefined entity
> Location: chrome://messenger/content/messenger.xhtml
> Line Number 905, Column 3:
>    <key id="openLightningKey"
> --^
> "
> 
> Thunderbird running on UbuntuMATE 20.04, had not presented this
> problem.

What is the version of Thunderbird you have installed?

I'm running Thunderbird 68.10.0 under Mint 19 and there is no such file 
as the one mentioned (in /usr/lib/thunderbird/defaults/messenger) and 
not under ~/.thunderbird either).

Can you send me the file off-list? It's possible they have made an error 
in the file — XHTML does not declare a <key> element type, so as it 
stands the error is correct: it's undefined.

Peter