This link shows two solutions:
I tried Solution 1 first and it failed. I tried solution #2 and it failed at this step: sudo pacman -Sy gnupg archlinux-keyring manjaro-keyring
The failure is as follows:
sudo pacman -Sy gnupg archlinux-keyring manjaro-keyring ✔
:: Synchronizing package databases...
core is up to date
extra is up to date
multilib is up to date
warning: gnupg-2.4.5-1 is up to date -- reinstalling
warning: archlinux-keyring-20240609-1 is up to date -- reinstalling
warning: manjaro-keyring-20230719-2 is up to date -- reinstalling
resolving dependencies...
looking for conflicting packages...
Packages (3) archlinux-keyring-20240609-1 gnupg-2.4.5-1 manjaro-keyring-20230719-2
Total Download Size: 3.84 MiB
Total Installed Size: 11.38 MiB
Net Upgrade Size: 1.66 MiB
:: Proceed with installation? [Y/n] y
:: Retrieving packages...
archlinux-keyring-20240609-1-any 1193.9 KiB 2.46 MiB/s 00:00 [--------------------------------------------------] 100%
gnupg-2.4.5-1-x86_64 2.7 MiB 4.81 MiB/s 00:01 [--------------------------------------------------] 100%
Total (2/2) 3.8 MiB 6.37 MiB/s 00:01 [--------------------------------------------------] 100%
(3/3) checking keys in keyring [--------------------------------------------------] 100%
downloading required keys...
:: Import PGP key 9B7A287D9A2EC608, "David Runge <dvzrv@archlinux.org>"? [Y/n] y
:: Import PGP key 6D42BDD116E0068F, "Christian Hesse <eworm@archlinux.org>"? [Y/n] y
(3/3) checking package integrity [--------------------------------------------------] 100%
error: gnupg: signature from "David Runge <dvzrv@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/gnupg-2.4.5-1-x86_64.pkg.tar.zst is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n] y
error: archlinux-keyring: signature from "Christian Hesse <eworm@archlinux.org>" is unknown trust
:: File /var/cache/pacman/pkg/archlinux-keyring-20240609-1-any.pkg.tar.zst is corrupted (invalid or corrupted package (PGP signature)).
Do you want to delete it? [Y/n] y
error: failed to commit transaction (invalid or corrupted package)
Errors occurred, no packages were upgraded.
Moderator edit: In the future, please use proper formatting: [HowTo] Post command output and file content as formatted text