When doing the regular updates to my Ubuntu laptop this weekend, I got prompted about an upgrade to version 16.04 (I am on 15.10 currently).
As all updates and upgrades have been smooth and without any problem before, I gladly pushed that button.
In retrospect, I should have been more careful.
The upgrade as such went without any hassle, even though it took quite some time, but no errors or any other messages shown.
It all started when login in the first time.
After entering the password on my account, the desktop is briefly shown with a pop up message about some System program problem detected, then immediately back to login screen.
No chance to read the complete message, nor to interact with the pop up buttons.
Same thing if I try the Guest login.
But doing CTRL + ALT + F1 to get a tty1 console, and I can login on my account.
So far so good, but what do I do now?
First thing first. Hook up an external USB disk, mount it, and backup the files I absolutely do not want to lose.
It is at times like these, you start to wonder when you made your last backup, and was that a complete backup or did I miss something.
This action was taken just to be safe, if I will end up in having to do a complete re-installation on the machine.
I really hope not to end up in that situation.
But as the saying goes, "Hope for the best. Prepare for the worst".
Scouring the net on the login loop problem, it seems to have happened before to people upgrading to other versions (14.04).
One of the solutions I found is.
mv .Xauthority .Xauthority.bak
and then reboot.
But that did not help on my computer. Obviously a solution for another problem.
Searching for the "System program problem detected", and found this to disable the reporting of program problems. Let's see if it helps somehow.
Remove all crash logs, and disable apport.
sudo rm /var/crash/*.crash
sudo vim /etc/default/apport
Change 'enabled=1' to 'enabled=0', restart system.
But this did not help either.
Continued searching, and found someone stating it could be video driver problem (again). Try,
sudo apt-get purge nvidia*
Doing this, I got a question on restart on how to proceed with graphics settings. I chose low quality for now.
I still get the 'system program problem detected' pop-up, but I can enter the desktop.
Finally able to login to the desktop, I notice that WiFi is not working any longer. Wonder what else has stopped working.
After some investigation.
lspci -knn | grep Net -A2
nmcli -p c
nmcli -p g
nmcli dev wifi
lshw -C network
It all looked okay. Ended up just de-selecting the Broadcom WiFi driver in Additional Drivers. Reboot. Then choosing that BCM driver again.
Viola! WiFi is working again. No good explanation on why it works, just happy it does.
While in the Additional Drivers, I also selected the Nvidia graphics driver again. And to my joy, I still am able to login.
Well that actually makes me think I am finally upgraded to Ubuntu 16.04 with everything working.