System Update froze - UbuntuMATE 16-04

[Colin Law]

On 21 June 2018 at 09:32, Bret Busby <bret.busby at gmail.com> wrote:
> On 21/06/2018, Colin Law <clanlaw at gmail.com> wrote:
>> ...
>> sync
>>
>
> After about fifteen minutes, no displayed response - cursor goes onto
> next line after the line in which the command is entered, an the
> cursor sits there flashing at me, in an otherwise blank line.
>
> So, the command "sync" also appears to have been hanged (and, yes, I
> do know the difference between hanged and hung :) ).

So it is that bug that you are hitting.  The update runs sync to flush
data to disc and that cannot complete for some reason.

> It surprises me that this bug original report is apparently 16 months
> old, and, apparently a critical bug, and, since then, two "point
> releases" and a new version (18.04) have been released, with this
> critical bug not being fixed, with the bug appearing to take 16.04
> from being a "stasle" release, to a status equivalent to Debian sid,
> with all that that name involves.
>
> I am now concerned that the bug may also apply to 18.04, as the bug
> has apparently not been fixed.

Yes I believe it does.  I guess the reason it has not been fixed is
that it is extraordinarily rare, as can be seen from the small number
of reports compared to, I guess, many many millions of times kernel
updates have been run.  The issue now is to find the problem on your
machine.  It could be hardware I imagine, being an issue with the disc
interface or disc itself in which case you are probably stuck.
Otherwise some process is hanging onto it and the only option is
probably to kill that process.  Someone may know how to identify which
process it is, but I don't.

Colin