Bing.com was down between about 6:30 and 7:00 PM Pacific Time on Dec 3, 2009. During this time, users were either unable to get to the site, or their queries were returning incomplete results page.

The cause of the outage was a configuration change during some internal testing that had unfortunate and unintended consequences.

As soon as the issue was detected, the change was rolled back, which caused the site to return to normal behavior. Unfortunately the detection and rollback took about half an hour, and during that time users were unable to use bing.com.

We strive to maintain a high standard of operational excellence at Bing. We are running a post mortem to find out how our software and processes need to be improved to prevent anything like this from happening again.

Satya Nadella
Senior Vice President, Online Services Division