How to fix sign-in error code 0x800488AB in the Xbox app for Windows 10

[Windows Central]

If you've been cursed by a sign-in error with the code 0x800488AB in the Xbox app for Windows 10, fear not, there is an easy fix.
The error window will tell you to go to Xbox.com and sign in to fix an issue with your account. But you don't need to do that. It doesn't fix anything, anyway.
Here's what you need to do.

Full story from the WindowsCentral blog...