As far as I know, the new launcher couldn't show the progress of patching, but it actually still do the patching in the background (your cursor sometimes blinking when the new launcher is open to indicates the patching is in progress)
by switching to the old launcher, you could see the progress...

SE twitter confirm this : https://twitter.com/FF_XIV_EN/status...70193538031617

if you talk about the [random error code], some of my friends said it usually because of vpn, either you need to use vpn or you should turn off your vpn, or something like that