To fix the Failed to Authenticate error in Diablo Resurrected, you will need to restart your router, restart your game, or check if the servers are down. Also, check to see any pending updates or even verify your files using the battle.net app.
Checking your internet connection or restarting your system are also good options. Then finally comes uninstalling. Only use this method if all else fails, and make sure to check for server status before uninstalling.
If the servers are down, it's most likely the cause of the hole error, and at that point, it becomes a waiting game.
Wait a few hours and check back later, and the servers will most likely be back up, allowing you to create a character and play with friends and the like.
That said, you can check server status by viewing sites such as down detector, official social media for the game, and the official forums on bilzzard.net.
If you find someone experiencing the same issues as you, chances are the servers are to blame. The same goes for if you see the down detector site displaying that the servers are wonky or down. Overall, just give it a few hours, and the servers should be back up in no time.
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