I’ve tried to track down the problem, but I’m totally at a loss for what to look for/at. I don’t think I’ve changed anything recently, I just rebooted to get a fresh start and I can’t get to any gui anymore. Pacman says all packages are up to date and this is the only problem I see in journal to. Any ideas?
You can go to the tty, and type lightdm -v to make sure it’s still installed.
If it is, try:
systemctl enable lightdm.service
systemctl start lightdm.service
You can use systemctl status lightdm.service to see the status of the service.
I tried those, and it just came up with the same error. It is installed, and the status command says it failed with the same error too.
Here’s the status:
http://aptget.xyz/0m2Dx/stat.txt
Please try to run lightdm in debug mode:
lightdm --debug --test-mode
Maybe there is a hint, where it hangs.
Here’s a picture of the output, I can’t get it into a text file for some reason.
Edit: btw I ran it with sudo because it seemed to not have permission for a lot of stuff without it
It says at the top:
Could not run plymouth --ping
Where is this coming from?
As far as I could tell, it’s not required to run and it’s not installed unless for some reason you install it manually
I had pretty much the same problem today when rebooting after updating 100 - 200 packages.
Here’s how I recovered it, thanks to amazing people on the internet 
Reboot.
Wait for the hardware to finish booting up - I get some text from the motherboard which then disappears.
Hit alt-f2 to get to a command prompt.
Logged in with my usual account which has admin privileges and used the following commands (some may need to begin with "sudo " if you get the error that you don’t have privileges):
“startx” - gave the error ‘No screen found’ and suggested looking into the log file, which for me was at /var/log/Xorg.0.log, and look for the first error line indicated by ‘EE’.
This showed that the failure was with the initialisation of the nvidia kernel module.
“mhwd -li” - lists video drivers. The offending driver was ‘video-nvidia-440xx’.
“mhwd -a pci free 0300” - installs open source driver.
“mhwd -r pci video-nvidia-450xx” - removes the offending driver I found 2 steps above.
Reboot.
This worked for me, and I’m happy not to use the proprietary nvidia drivers, the free one is fine, as far as I can see.
Hope this helps someone in the same predicament I found myself in, earlier today.
So my lighten won’t start as well. Most people seem to think it’s their drivers. I’m running AMD free drivers and experiencing the same issues. I can’t seem to find a consistent answer on why the update broke my system.
Hello,
This didn’t worked for me.
The welcome window appeared but after login the windows freezes and I can not click in any icon.
I did the following.
mhwd -r pci video-linux
mhwd -r pci video-nvidia
sudo mhwd -a pci nonfree 0300
reboot
And everything worked.