Hi,
I’m posting this because I ran quite mad trying to solve this issue despite the numerous posts on various arch forums giving commands which was not working for me, like :
sudo pacman -Sy endeavouros-keyring
sudo pacman -Syu
If, like me, you have randomly tried lots of commands but the issue persists, try the following commands to clean and start anew (from french post : https://forums.archlinux.fr/viewtopic.php?style=9&t=22949 but adapted to endeavouros) :
First manually download keyring package from some mirror like : https://mirrors.jlu.edu.cn/endeavouros/repo/endeavouros/x86_64/
You can check in your mirror list file :
cat /etc/pacman.d/endeavouros-mirrorlist
Then do the following :
rm -rf /etc/pacman.d/gnupg
pacman -U /path/to/downloaded/keyring/package.pkg.tar.zst
pacman-key --init
pacman-key --populate archlinux endeavouros
sudo pacman -Syy archlinux-keyring endeavouros-keyring
pacman -Suu
After then Manuel is no longer a problem.
Hope it will help someone.