Error “error: failed to commit transaction (invalid or corrupted package)” (SOLVED)

When using pacman while updating packages, for example

sudo pacman -Syu

An error may occur:

error: binutils: signature from "Frederik Schwan <frederik.schwan@linux.com>" is unknown trust
:: File /var/cache/pacman/pkg/binutils-2.39-4-x86_64.pkg.tar.zst is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n]

If you choose the proposed option – remove an invalid or damaged package – then the update will fail with the following error:

error: failed to commit transaction (invalid or corrupted package)
Errors occurred, no packages were upgraded.

The specific error message in your case may be different, for example, another package may be invalid or corrupted, or the PGP signature may belong to another person.

In any case, to fix the error, start by reinstalling the archlinux-keyring package:

sudo pacman -S archlinux-keyring

After that, the system update should pass without error.

sudo pacman -Syu