I tried the update on two PCs yesterday, a desktop and a laptop. It failed on both.
On the desktop, pamac got terminated out of nowhere (seems to happen to other people as well) while downloading. Download was suspiciously slow (that might just have been a slow mirror), and at 1.8GB/3.2GB it just said “Terminated” and I was on the shell again. I tried running pamac again, but it just said it’s waiting for a running package manager to exit.
Assuming it might still run in the background and start applying updates without me seeing the progress, and also assuming it’s still in the download phase, I rebooted the PC.
After reboot, I got a “you need to load the kernel first” message. I could boot a snapshot and restore that, after which a second attempt to apply the update worked (didn’t seem to download anything, so I assume the indicated download progress in the first try was off).
On the laptop, the update went through without any apparent issue (download was suspiciously fast though), but upon reboot it … can’t? “Timed out waiting for device” (this is after entering the password for the encrypted device). See picture. I haven’t tried to fix it yet. I hope live image + chroot + retry update works. If you have other pointers, let me know. Luckily the laptop isn’t that important so if all else fails I can just nuke it and reinstall from scratch, but I’d rather try to fix it first.