I recently had an issue with Gnome on Arch Linux during the system boot. After turning my computer on, I saw gray screen with message like:

Oh no! Something has gone wrong. A problem has occurred and the system can't recover...

and I couldn’t log in or do anything and started searching solutions for this problem via my phone. First, I switched to terminal mode with Alt+F2 (you can switch back to GUI with Alt+F1), logged in and updated system via pacman: sudo pacman -Syu. I tried to install or reinstall different packages mostly related to graphic card drivers, X11 or Gnome, but it didn’t help. Luckily, I found this thread on the Arch Forums, where there was a post suggesting disabling Wayland on GDM by opening /etc/gdm/custom.conf file and uncommenting line with

WaylandEnable=false

I did that. After restart, it finally fixed this problem and Gnome was loaded succesfully. That was the first time I had an issue with Boot related to Gnome and Arch. Fortunately, thanks to good community, I was able to fix it pretty quickly (in ~30 minutes) and avoided system re-installation. After that, I also had a few issues with sound on Bluetooth devices, but I fixed them quickly too.

I hope, you’ll find this post useful in case of having similar problems.