No option to switch from xorg to Wayland on Ubuntu 17.10 login

That means Wayland is disabled by your hardware and choice of drivers for it. You need to switch to nouveau to get Wayland working.

You might face this issue once you do it: GNOME has grey bar on top and bottom after upgrade from 17.04 to 17.10, how do I fix it to how it's supposed to look?

That means Wayland is disabled by your hardware.

Thanks, I did read on Didier Rocks that Wayland is disabled and falls back by default when proprietary Nvidia drivers are used. – user299070 yesterday

I am not a huge fan of the Linux Nvidia drivers*, but once in a while I try them to check the performance of the machine. More often than not, I end up in a console and no X/Wayland.

I have seen some Ubuntu users reinstalling their machine after this f* up, so here's how to fix it (I always forget the initramfs step and end up wasting a lot of time):

$ sudo apt-get remove --purge nvidia-*
$ sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf_pre-nvidia
$ sudo update-initramfs -u
$ reboot