Posts made by Luksonowsky
I've been facing same issue as you but I found sollution, at least for me (game was working well for about 1.5h). There is post on reddit:
Go to the location of your AC Valhalla download. Mine is in Documents/Assassin's Creed Valhalla. As soon as you open that, you should see two folders and one file: cache, file_cache, and ACValhalla.ini, respectively. If you just open the .ini file and scroll down until you see WindowMode=2 (18th line). Change the 2 to 1, don't change anything else in the window settings there. Save the file and close, launch game. It may crash the first or second time you load it after this, but I just restarted my computer and the game has been working fine after that.
You can try it, good luck