it is reported by many users that updating with pamac or pacman is giving error on keyrings and failed to proceed, at the moment, but there is a simple solution:

reinitiate keyrings is reported to help here from multiple users:

sudo pacman -Sc
sudo pacman-key --init
sudo pacman-key --populate archlinux antergos
sudo pacman-key --refresh-keys
sudo pacman -Syyu

run this commands line by line from terminal…