pamac is still corrupting databases under some circumstances
Created by: severach
All too often pamac is leaving the db files damaged. pamac doesn't work well with damaged db files. pacman -Syu
reports these errors.
error: could not open file /var/lib/pacman/sync/core.db: Unrecognized archive format
error: could not open file /var/lib/pacman/sync/multilib.db: Unrecognized archive format
pacman -Syyu
immediately fixes the problem.
My guess is that you're downloading directly to the db files which you should never do. You download to temp files and move (not copy) them into place when complete and tested.
% pacman -Q pamac-aur
pamac-aur 4.3.3-1