If you have an issue updating or installing something, there's one solution that will almost always work. Try this first before asking:
sudo rm -f /var/lib/pacman/db.lck && sudo pacman-mirrors -g && sudo pacman -Syyuu && sudo pacman -Suu
It will remove the database lock file (happens if pacman was suspended unexpectedly), it updates the mirror list, it updates the repos, and it also installs all updates and downgrades (if necessary first manjaro-system and pacman, and then the rest).
Unrelated protip: If you don't want pacman-mirrors to go through all the mirrors every time it runs, do "sudo pacman-mirrors -i" to select you favourites.