In some cases, when you are running or logging in to the client application or the game, you may need to reset the app/computer or even reinstall the app. Note that the game does not work on older systems than Windows 10. Also, make sure that you have a stable internet connection, check for game updates, update the graphics driver and operating system. If you have problems with running the game, try restarting your computer after installation. Error: Failed to initialize Graphics Device.
On this page of the guide to Diablo 2 Resurrected, you will find information and tips on what to do if you have problems with the game or it won't start at all.