Upgrade from 16.04.x to 18.04.3 broke system - was Upgrade paths from UbuntuMATE 16.04.x and 18.04.x to 19.10

[Bret Busby]

It occurred to me that I should repost the message below, with a
subject that better indicates what has happened.

---------- Forwarded message ----------
From: Bret Busby <bret.busby at gmail.com>
Date: Sun, 13 Oct 2019 23:02:13 +0800
Subject: Re: Upgrade paths from UbuntuMATE 16.04.x and 18.04.x to 19.10
To: "Ubuntu user technical support, not for general discussions"
<ubuntu-users at lists.ubuntu.com>

On 13/10/2019, Petter Adsen <petter at nillabs.com> wrote:
> On Sat, 12 Oct 2019 15:43:30 -0400
> Paul Smith <paul at mad-scientist.net> wrote:
>
>> On Sun, 2019-10-13 at 00:31 +0800, Bret Busby wrote:
>> > I am assuming (but am not sure) that I can upgrade directly from
>> > 18.04.x. to 19.10.
>>
>> I don't think that is correct.  Technically the supported release path
>> from 18.04 to 19.10 requires you to go 18.04 -> 18.10 -> 19.04 ->
>> 19.10.
>
> True. In this scenario I would consider just doing a clean install.
> I've upgraded through several releases this way before with luck, but
> it might be easier to just install a fresh system from the release
> candidate images.
>
>> You can upgrade from one LTS release directly to the next LTS release
>> (e.g., 16.04 -> 18.04 is supported, and 18.04 -> 20.04 will be
>> supported next spring).  But for non-LTS releases the supported
>> upgrade path is to go through each one.
>
> Also true, but the supported upgrade path from 18.04 to 20.04 will only
> be opened after the first point release, which will happen a few months
> after release (so not in the spring).
>
> Petter
>
> --
> "Chaos, panic and disorder. My work here is done." --Anne Onymous
>

The work of Annie Ominous, appears to have been done by the software updater.

On one of my 16.04.x systems, I tried the following upgrade path.

1. Using the Software Updater, check and install all updates, to make
the system fully updated for 16.04.x. That (appears to have) worked.
Rebooted.

2. Using the Software Updater, which, upon rebooting, displayed the
notification that an update to 18.04 is available, selected the
Upgrade System (to 18.04) option. That appeared to have worked, with
lots (about 266) of packages to be removed.

Rebooted.

Broken.

Upon rebooting, I get the GRUB menu, either wait for it to timeout and
boot by default into Ubuntu, or hit <Return> with the default
highlighting being for Ubuntu, and I get, first, the terminal level
login displayed, then the screen goes black, then I get, in the middle
of the screen, the UbuntuMATE logo, with the five dots below it, with
them taking turns to change from white to green and back again, below
the logo.

Then, after a minute or two of that, the screen goes black, and stays black.

After at least en minutes of waiting, with no visible change, I use
<CTRL><ALT><F1>, get console mode, which shows me that the system is
now 18.04.3 LTS.

I can log in at the console mode, in either of two user accounts, and,
upon running
sudo apt check
no problems are shown.

At the console prompt, when logged in, if I enter
startx
I get a screen with, and, only with, a default green background, displayed.

If I then enter <CTRL><ALT><F7> I again get the black screen.

With the green background screen, if I use the non-dominant mouse
button, a menu dialogue box is displayed, but no option that appears
to me to be useful in this context, is displayed.

The computer to which this applies, is the computer to which my
previously stated problem of losing use of the GUI for me as the
primary user, due to a panel problem, then, being able to add a second
user, and, logging in as the second user, gave me access to the GUI,
as the second user, also applies, so I do not know whether this
upgrade problem, is related to that problem.

After the failed upgrade, I can no longer reach a GUI login screen,
upon booting - the GUI appears to have been destroyed by the upgrade
from 16.06.x to 18.04.3 .

10-20 years ago, from memory, a command line procedure existed, for
upgrading from one version to the next version (in this case, for
example, trying to upgrade from 18.04.3, to 18.10.x, to find whether
that could solve the problem of the lost GUI), but, I do not remember
what was the command line procedure for doing that.

So, how can I fix this, and, regain my GUI, to get the computer working again?

System (version number) updates appear to be increasingly troublesome.

Thank you in anticipation.

-- 
Bret Busby
Armadale
West Australia
..............

"So once you do know what the question actually is,
 you'll know what the answer means."
- Deep Thought,
 Chapter 28 of Book 1 of
 "The Hitchhiker's Guide to the Galaxy:
 A Trilogy In Four Parts",
 written by Douglas Adams,
 published by Pan Books, 1992

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