I'm relatively new to gnome (antergos in this case) or to linux in general. I'm not quite sure how to help but my dock disappeared after the last arch linux update. The gnome website shows an error icon and the mouse-over description says 'undefined'.

EDIT:
[jaba@jaba-x260 ~]$ uname -r
5.0.3-arch1-1-ARCH
Hi,
I had the same problem. When running pacman -Suy you probably got this error message or something similar.
warning: dash-to-dock: local (1:64-4) is newer than core (66)
This prevents the system from updating your package.
Solution: Try running pacman -Suu. This will "downgrade" your package and after a reboot you should have the newest version running and everything should work again. I suspect the version numbers are confusing pacman.
Thanks a lot. Got fixed after updating my system.
Most helpful comment
Hi,
I had the same problem. When running
pacman -Suyyou probably got this error message or something similar.This prevents the system from updating your package.
Solution: Try running
pacman -Suu. This will "downgrade" your package and after a reboot you should have the newest version running and everything should work again. I suspect the version numbers are confusing pacman.