The Bing and Yahoo! search engines were both unavailable for much of the business day on January 2. The outage lasted from approximately 11:30-3:00 PT.

Reuters reported that the outages were caused "after Microsoft pushed out a bad code update and then struggled to roll it back."

Engadget reported that: "Because Redmond's roll-back didn't work, it had to turn off groups of linked servers to get back to the point where things were working as they did pre-crash."

Yahoo! was affected because its search has been powered by Microsoft's Bing search engine since 2009, under a 10-year agreement. In a brief written statement, a Microsoft spokesman confirmed the outage, to Reuters but declined to comment on the cause. Yahoo did not immediately respond to reporters' requests for comment.

Other Microsoft cloud services like Outlook.com, Hotmail.com, Live.com, and the Cortana virtual assistant from the company's mobile phones were also affected.