Hi, I was testing endeavor out on a VM: after several successful online installs where I was trying out different desktops. I got this error.
I thought it could be the ISO file getting corrupted, so I downloaded it again and loaded it up. Still no dice.
I looked through the forums and tried the solution listed here, but that also failed.
I tried doing it after running sudo pacman -Sy archlinux-keyring. I ran a speed test during a failed attempt to make sure my internet was working and I had 91mbps.
It looks like there is a recent change to the Arch repos. The reiserfsprogs package was removed.
As a workaround until we can put a fix in place you can edit the file /etc/calamares/modules/pacstrap.conf and remove the line with reiserfsprogs. You need to do that before launching the installer.