Would you mind following these steps:
sudo rm /var/lib/pacman/sync/*
sudo pacman-key –init
sudo pacman-key –populate archlinux manjaro
sudo pacman -Syyu
A trusted user wrote a piece on how to deal with such errors more persistently. Check it out here.
Moderator edit: In the future, please use proper formatting: [HowTo] Post command output and file content as formatted text