sudo pacman -Sy archlinux-keyring
sudo pacman-key --populate archlinux
sudo pacman-key --refresh-keys
one error you are possibly getting
installing<PKG-HERE> breaks dependency <PKG-HERE>
ERROR FIX FOR:
: Starting full system upgrade...
resolving dependencies...
looking for conflicting packages...
error: failed to prepare transaction (could not satisfy dependencies)
:: nvidia: installing nvidia-utils (390.42-1) breaks dependency 'nvidia-utils=390.25'

#!/bin/bash
Upg Ignore Shell Script || flag 1
sudo pacman -Syyuu --ignore $1
yaourt -Syyuu --ignore $1