ArchLinux Upgrade Issues

Error: key "ABCDE1282828181" could not be looked up remotely

Upgrade archlinux-keyring: pacman -S archlinux-keyring

Unable to get past login window after upgrading

This is caused by Nvidia driver being upgraded

nvidia-dkms: pacman -S nvidia-libgl

Failed to start load kernel modules after upgrade:

Possible causes:

broadcom-wl module

Solved by re-"makepkg" broadcom-wl from AUR

Find error message in systemctl status systemd-modules-load.service