Your package sigs are out of date. Code: rm -R /etc/pacman.d/gnupg pacman-key --init pacman -Syy pacman-key --populate archlinux pacman -Syu You should pick whatever mirror is fastest for you. See: Sorting Mirrors This may also happen to manjaro users. If you're using Manjaro, you need to do "pacman-key --populate archlinux manjaro" instead.
rm -R /etc/pacman.d/gnupg pacman-key --init pacman -Syy pacman-key --populate archlinux pacman -Syu