According to Microsoft, it was a “networking configuration issue” that took down a plethora of the company’s services for several hours. In the early (U.S.) hours of January 25th, Microsoft made an announcement recognizing user reports of a worldwide outage of services. According to reports, the outage affected services across the board, including Outlook, OneDrive for Business, Microsoft Graph, Microsoft Teams, Xbox Live, Exchange Online, PowerBi, Microsoft 365 Admin Center, and SharePoint Online.
We've rolled back a network change that we believe is causing impact. We're monitoring the service as the rollback takes effect.
— Microsoft 365 Status (@MSFT365Status) January 25, 2023
See also: FAA’s grounding of all U.S. flights points to vastly outdated technology
Upon recognizing the issue, Microsoft confirmed they were looking for a solution that would not cause any additional negative impact to users. In the end, at 4:26 am ET on the 25th, the company stated they had rolled back the network change that had caused the issue, and would be monitoring the statuses of all services to ensure that the issue had been solved.