Hello Sincerus, Annette Khalifa,
Welcome to Microsoft Q&A forum.
Thank you for sharing your issue, you are not alone in this, I've seen multiple users reporting the same issue. The most common point I see in them is that they seem to come from the UK and related to an online safety act that require age verification.
If this applies to you, can you please try to sign in to xbox.com/live and either skip or verify your age? After that you can try to sign in again.
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