Update Failure w/ GPME Error

Removing the remote databases and their signatures should help in your case:

sudo rm -r /var/lib/pacman/sync/


sudo pacman -Syu

Also, running yay with -Syu is not necessary. Just yay is sufficient.

Why this happens?

Some mirrors are wrongly configured, broken or the mirror URL in the pacman.conf is set up incorrectly and instead of returning a proper HTTP error they will send actual data (usually some fancy HTML with a textual 404) which pacman will interpret as the signature being available and write it to that *.sig file, pass the same data on to gnupg which then fails to verify the signature since all it got was some “garbage”. That’s when you get that No data error.