[2021] I got this pop up just now. I quickly went to my Activision account and changed my password successfully. I also checked if I had 2 factor authentication and I did. What happened? Did someone try and hack me?

Thanks for the notes in this thread, everyone. We experienced a server issue that coincided with these reports. The simplest explanation to provide is that players reconnected faster than the server disconnected them, which prompted an "Another user has signed in using this Activision account" error.

We'll continue to monitor server stability. Feel free to update your accounts accordingly if wanted. I recommend visiting Keeping your Activision Account Secure for advice on security best practices.