I also encountered the same issue as you, but I accidentally fixed it. Now, I’ll share how I fixed it, hoping it can help you too :) [b]PS:My native language is Chinese, so some of the English may not be easy to understand, please forgive me[/b] first I searched on Google and found that Steam’s OpenID has been disabled, which caused me to be unable to log in (yesterday I changed my Steam ID to play HELLDRIVERS 2) This led to the 'Authentication Error' popping up when I tried to log into DIM today. Then I asked ChatGPT and came to the following conclusion： Find DIM Cache Directory，Delete Cache Files， Restart DIM Then I tried various methods to clear the cache, but nothing worked, and the 'Authentication Error' kept showing up. So I changed my Steam ID back to the original one and continued trying to log in. The result? Just like you, it kept looping. At that point, I thought maybe I should post on Bungie’s discussion platform. But then I realized I hadn’t logged in yet, and if I used Steam, I wouldn’t be able to log in. So I tried EPIC, but it also showed an issue. Then I tried XBOX, and it logged in successfully. That’s when I saw your post and thought I’d log into DIM to show the error link, and unexpectedly, I just logged in. It was really strange. [u]DIM cache files are typically stored in one of these locations on your computer:[/u] [b]Windows: C:\Users\[Your Username]\AppData\Local\DIM Windows (alternative location): C:\Users\[Your Username]\AppData\Roaming\DIM[/b] Note: The AppData folder is hidden by default. To view it, enable the option to show hidden files in your file explorer by clicking "View" at the top and checking "Hidden items."