[PLUG] ubuntu-mate, gnome-3, power fail

[Keith Lofstrom]

Thanks for good ideas about UPS ...

The REASON that restoring my UPS is urgent was that an
unfortunately timed power glitch left my main working
desktop in a borked state. 

By way of background, I hate video games, so instead of
gnome3 I normally use an Ubuntu-mate (gnome-2 clone)
desktop. 

After the power glitch, my Ubuntu-mate desktop came up
in a poorly configured version of gnome-3, difficult
to use at the best of times and execrably awful when
mis-configured.  This was difficult to understand,
especially with no "video game mouse skills".  I could
only access it by ssh from a different system.

Cutting to the chase, the problem happened becuase the
system was in the middle of installing  autoupdates
when the power glitched.  The install did not complete,
nor leave an understandable audit trail. 

When I finally managed to diagnose this yesterday evening,
I found an error message flying past during boot,

   Failed to acquire org.gnome.SessionManager 

and buried before that:

   Could not acquire name on session bus

The intertubes led me to the fix; editing 

   /etc/X11/Xsession.d/80mate-environment

then adding the line:

   unset DBUS_SESSION_BUS_ADDRESS

before the closing "fi".

My ubuntu-mate desktop (20.04) is back to working,
and boots properly. 

But not for long; after completing some other urgent
tasks (replacing the tarp that tore off the greenhouse
in recent high winds, etc.) I will finish transferring
my working environment to a debian-mate machine, and
exile ubuntu-mate to offline backups.

Perhaps a similar problem will occur with debian-mate
someday, but at least I won't have a thicket of opaque,
incomprehensible "snap" packages to contend with.

Keith

-- 
Keith Lofstrom          keithl at keithl.com