It just happens on my Rasperry pi: signature from "Arch Linux ARM Build System <email@example.com>" is unknown trust
I've started a regular update by using
sudo pacman -Syyu and the following lines where the final result.
warning: Public keyring not found; have you run 'pacman-key --init'? downloading required keys... error: key "77193F152BDBE6A6" could not be looked up remotely error: required key missing from keyring error: failed to commit transaction (unexpected error) Errors occurred, no packages were upgraded.
I did what was told me to do ;-).
sudo pacman-key --init
And after running
sudo pacman -Syyu I was asked.
:: Import PGP key 4096R/68B3537F39A313B3E574D06777193F152BDBE6A6, "Arch Linux ARM Build System <firstname.lastname@example.org>", created: 2014-01-18? [Y/n]
"As expected, I though" but than I got a long list of the error mention in the headline (for each package).
I've fixed this by executing the following command.
pacman-key --lsign-key 77193F152BDBE6A6
sudo pacman -Syyu was running fine as expected.
Strange note, all was working fine a week ago (2018-05-25) and the pgp key was created 2014 :O.