Please note that pamac is only one of the options for updating and installing. The native package manager for Arch-based distributions is pacman — which is a command-line-only tool — and yay for AUR stuff. In addition to that, if you want a graphical package manager front-end, then you can also use octopi, although that doesn’t come installed by default anymore.
The above all in mind, you can update your system with…
sudo pacman-mirrors -f && sudo pacman -Syyu && yay -Su
That all said, even though pamac is a bit of a problem child, we can only help you debug the problems you’re having with it if you give us the exact and correct information of why you cannot use it anymore. This means that we need to see the error messages verbatim.
