UPDATE: 8.05pm: Microsoft says Xbox Live sign-in troubles should now be resolved. "Users should now be able to sign into Xbox Live on all platforms," it wrote in an update tweet on its Xbox Support feed. "Please give it another try and let us know if you're still running into issues."
Users should now be able to sign into Xbox Live on all platforms. Thanks for hanging in there while things got sorted out. Please give it another try and let us know if you're still running into issues. We're here an listening. https://t.co/cTnFVSigmD— Xbox Support (@XboxSupport) November 10, 2020
ORIGINAL STORY 7.03pm: Today marks the official start of the next console generation, thanks to the arrival of Microsoft's Xbox Series X/S, and it looks like Xbox Live is struggling to cope with the strain of new console owners eager to take their shiny new hardware for a test drive online.
Xbox Live sign-in issues have been reported from all corners and are affecting all Xbox platforms - that is Xbox, Xbox.com, Windows Phone, and Windows 10 - but it's likely to be a particular frustration for those Xbox Series X/S players trying to log-in and download their previous digital purchases onto their new console.
The good news is that Microsoft is on the case, and has acknowledged customer reports via its Xbox Support Twitter feed, telling users that it's aware of sign-in problems, and that "the right teams are looking into the issue and working on a fix."
We're aware that users are currently unable to sign into Xbox Live on various platforms. The right teams are looking into the issue and working on a fix. We'll provide updates here on our Twitter, or on our status page at https://t.co/dG2dbISiH7— Xbox Support (@XboxSupport) November 10, 2020
The official Xbox Live Status page has offered a further update regarding problems with Microsoft's core Xbox Live services, writing that "We are seeing indications that we are on the path to recovery with this feature, and we expect to be back up and running shortly."
I'll update this story as more details emerge.