Solution:

First make sure the first mirror in [sudo vim /etc/pacman.d/mirrorlist] is whitelisted
Then:

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

If you use e2guardian, make sure ‘blanket block for SSL’ is not enabled in [examplef1.story].
Then

sudo -E pacman -Syu

Note: I don’t understand the meaning of the above two sentences. I’m in raspberry pie (armv7). An error occurred in the title after installing archlinux. Found a lot of methods, did not find a solution. Finally, I saw something about this website. Just give it a try. But I don’t know what he said..