Microsoft account holders are currently experiencing problems when they try to login to their accounts. The error appears after they have entered their email address and says: “This username is not included in our system. Make sure you entered the name correctly. Otherwise, contact your administrator.”
In case you stumble upon this error, don’t panic however as your account hasn’t been deleted or hacked. It’s a simple error caused by Microsoft’s ongoing transition to the new login page. We do expect the company to fix this issue soon.
Meanwhile, you can login into another Microsoft service and then come back to the original login page and try again. For example, if you’re facing issues with Outlook, login into Microsoft Store and then come back and try logging into Outlook. That should fix the error.
Microsoft hasn’t released an official statement yet so we will have to wait to know what went wrong and when it will be fixed.