Cannot upgrade Archlinux (pacman -Syu not working)

I just had this very same error. The problem seems to be that there are new keys in the archlinux-keyring package, and new packages (confuse) signed with those keys. Since both packages are updated in the same transaction, well the new keys cannot be used until the update is finished, but the transaction will not start until the packages are checked...

The solution would be to update the archlinux-keyring by itself:

pacman -S archlinux-keyring

And then do the rest:

pacman -Su

If that fails, you could try running through the keys manually, with:

pacman-key --populate

but usually, it is not necessary.

I just happened to have the same problem, and solved it the following way:

$ sudo pacman -Rdd package-query # Purge the conflicting package-query
$ sudo pacman -Syu               # There it works

# Now reinstall package-query
$ git clone https://aur.archlinux.org/package-query.git
$ cd package-query && makepkg -si