It was mentioned in the first post of this thread, as well as in the second post.
You are supposed to check the forum before applying the update, and I always advise to update the system by way of pacman from a tty, while completely logged out of your GUI session. Afterwards, you can use pamac (or yay) for the AUR stuff.
The pamac GUI is useful for if you want to install or remove software in between updates, and you can also get away with small updates — e.g. for a couple of fast-tracked packages — but for a bundled update such as this one, you will be better off running it from a tty. 