Hello,
I’m posting a reply to let topic starter and others know that I have the exact same problem, also at the exact same percentage (39%). Only difference is I have a completely different computer; being a laptop with a (non-overclocked) i9-13900H, 32GB RAM and RTX 4080 mobile.
It used to run Diablo 4 fine. I tried updating, ran into the error. Then uninstalled the game, now the same error appears when I try installing. Scan & repair does not help.
Any help would be greatly appreciated 