I read the Arch linux announcement Arch Linux - News: Cleaning up old repositories.
It says that old repositories have been cleaned up on 2025-03-01. That date might explain why I recently received the error on <pacman -Sy> and on pamac update.
So I looked into my /etc/pacman.conf file.
The following searches did not yield a result: [community-testing], [testing], [testing-debug], [staging], [staging-debug].
Only if I searched for [community], I saw the lines 82-84:
[community]
SigLevel = PackageRequired
Include = /etc/pacman.d/mirrorlist
I also saw a file /etc/pacman.conf.pacnew; in its first line I saw the comment
'# /etc/pacman.conf.
From that I concluded that I should
- delete the pacman.conf and
- rename pacman.conf.pacnew to pacman.conf
I also saw pacman-mirrors.conf and pacman-mirrors.conf.pacnew. Probably I should do the similar change, i.e.
- delete the pacman-mirrors.conf and
- rename pacman-mirrors.conf.pacnew to pacman-mirrors.conf.
I also saw 2 files pamac.conf and pamac.conf.pacnew. I decided to
- remove pamac.conf and
- rename pamac.conf.pacnew to pamac.conf.
After these changes I could invoke the pamac GUI and update my Manjaro system.