Windows Phone 8.1 logon problem solved!
The annoying problem with Windows Phone 8.1 is solved even though there is no official explanation!
If you recently reverted your Windows Phone 8.1 device to factory settings, or if you revert a Windows 10 Mobile phone to an older operating system, you may have noticed that you have not been able to log in to your Microsoft account. You may not even be able to disable “Reset Protection” without even going to the internece and finding a code.
Although no official explanation has been given by Microsoft about the reason for this, the issue seems to have been resolved. Both reset protection and access to the device can be performed without any problems.
However, it is not clear why this problem has occurred or why it does not affect Windows 10 Mobile devices. Part of the problem is that if you are on Windows Phone 8.1, you can not go back to Windows 10 without first downloading an application from the Windows Store, and you must be logged in with a Microsoft account.
Fortunately there seems to be no problem at this point, but Microsoft is still waiting for news.