Automatic

sudo pacman -S archlinux-keyring

Manual

https://forum.manjaro.org/t/signature-is-invalid/94500/16

  1. sudo pacman -Scc. answer y to everything
  2. sudo rm -r /etc/pacman.d/gnupg
  3. sudo rm /usr/share/pacman/keyrings/*
  4. sudo pacman-key --init
  5. sudo pacman -Sy archlinux-keyring
  6. It is ok to have errors in that update. Just reply Y
  7. sudo pacman-key --lsign-key 02FD1C7A934E614545849F19A6234074498E9CEE
  8. sudo pacman-key --list-keys to see if keys are [full]
  9. sudo pacman -Sy archlinux-keyring
  10. sudo pacman-key --list-keys
  11. sudo pacman-key --init
  12. sudo pacman-key --populate
  13. sudo pacman-key --refresh-keys. It is ok to have ALOT of errors here