Xbox's Chief Technology Officer, Scott Van Vliet, has publicly explained the cause of a system outage that disrupted sign-in, game libraries and game launching for many players from late Sunday night into Monday. He attributed the failure to an internal Microsoft licensing service shared across multiple products, which sits outside Xbox but is depended upon by it, and apologised, calling the disruption "unacceptable" while pledging that the company would "do better."

Van Vliet said the failure caused sign-in and entitlement checks to fail, preventing some users from viewing their full library or launching owned games, and also affected publishing and store partners, explaining why some games were hit while others were not. On-call teams identified the issue overnight via automated monitoring and declared a major incident, rerouting traffic to healthy infrastructure while recovery occurred unevenly across regions. Microsoft is now conducting a full post-incident review to strengthen the dependencies behind sign-in and game launches, the outage comes shortly after a similar prolonged PlayStation outage, and just ahead of this week's launch of Halo: Campaign Evolved.