Two games: Giana Sisters: Rise of the Owlverlord and Alan Wake's American Nightmare will not update or install since latest proteus update and subsequent hotfix. I keep getting "Disk access error.." I have tried running Galaxy as admin as admin as well as uninstalling and reinstalling the games on 3 different pcs and I get the same error.

You don't need the galaxy client to access your games. Best thing you can do, is uninstall the client, and forget about it.

Just download your games from your account HERE
Ignore the blue banner, and use the normal installers underneath.

I'm getting the same errors on other random games in the client too.

I like the client. I want the client.

Try crystaldiskinfo to check status of your disk, and change sata cable

I want the client too but this is kind of ridiculous after so long in "beta". I tried 3 different computers and ran f disk. probability of it being a dish error is low. Plus, I tried the standalone game installers and they worked fine. There is definitely a bug with the Galaxy client. I am going to uninstall galaxy. Hopefully it is better in a couple years.

I am sure those errors correct themselves with time, I suffered them sometimes if a lot of udates/downloads triggered at once.

I you want the client, an alternative, if your problem continues is downloading the offline installer, install your game with it and afterwards import the game to Galaxy.

Greetings

Looks like it was indeed a client bug. In the 2.0.50 Beta (May 9, 2022), under the General section they say "Fixed E4 installation error." My games have installed now.