Error while trying do downgrade postgres: package missing required signature

Hello everyone.

I’m trying to downgrade postgres from current version 14 to 13, following instructions on Using the pacman cache. Package file is in the cache, but can’t install it without signature.

root@sunce:[/home/eden]:ls -aF /var/cache/pacman/pkg/ | grep postgres                                                                                                                                                                                                                                                                                                                                                                    [1]
postgresql-13.4-4-x86_64.pkg.tar.zst
postgresql-13.4-6-x86_64.pkg.tar.zst
postgresql-13.6-1-x86_64.pkg.tar.zst
postgresql-14.2-1-x86_64.pkg.tar.zst
postgresql-14.2-1-x86_64.pkg.tar.zst.sig
postgresql-libs-13.4-4-x86_64.pkg.tar.zst
postgresql-libs-13.4-6-x86_64.pkg.tar.zst
postgresql-libs-13.6-1-x86_64.pkg.tar.zst
postgresql-libs-14.2-1-x86_64.pkg.tar.zst
postgresql-libs-14.2-1-x86_64.pkg.tar.zst.sig
postgresql-old-upgrade-12.8-4-x86_64.pkg.tar.zst
postgresql-old-upgrade-12.8-5-x86_64.pkg.tar.zst
postgresql-old-upgrade-12.9-1-x86_64.pkg.tar.zst
postgresql-old-upgrade-13.6-1-x86_64.pkg.tar.zst
postgresql-old-upgrade-13.6-1-x86_64.pkg.tar.zst.sig

root@sunce:[/home/eden]:pacman -U file:///var/cache/pacman/pkg/postgresql-13.6-1-x86_64.pkg.tar.zst
loading packages...
error: '/var/cache/pacman/pkg/postgresql-13.6-1-x86_64.pkg.tar.zst': package missing required signature

Any possible solution for this?

Also, I tried installing postgresql13 13.6-1 from AUR, but no luck. After building the package from the source, it fails on tests.

Please provide the output of cat /etc/pacman.conf