So, the time has come to upgrade my Ubuntu Server LTS 16.04 to the latest LTS 18.04…

It’s a straight-forwards upgrade, easy-peasy, right?

The Triumph Defeat of Hope Over Reality

Compared to what Linux used to be in the recent past, the upgrade via the stock 16.04 UI went fairly smooth…

I already knew that I had to do the standard ZFS pool upgrade:

sudo zpool upgrade <poolname>

But after the whole upgrade was done, I tried to VNC into the machine again after it rebooted… and failed.

2018/12/25 Update:

I suddenly noted that my Unifi Controller was no longer working… I later discovered that it was due to the Ubuntu LTS upgrade… Another day, another battle…

DMs

Display Managers are to blame… Specifically, GDM.

Canonical made the switch from LightDM to GDM, but GDM does not play nice with x11vnc, because it creates a separate display after successfully logging in (even when on the console)…

So, a quick fix was found to revert display managers… Since I upgraded and LightDM was still installed, all I needed to do was run dkpg-reconfigure:

dpkg-reconfigure lightdm

Then, select “lightdm”, done!

No fluffing around with /etc/gdm3/custom.conf attempting to disable Wayland, no need for some silly double-VNC connection…

BTW: if you happen to be doing a fresh install, I believe these instructions may help (I have not tried them).