Facebook: Outage caused by routine maintenance error

Details: Facebook vice president of engineering Santosh Janardhan explained in a blog post that the outage, which knocked Facebook, Instagram and WhatsApp offline for billions of users, happened during regular maintenance operations in which parts of the servers are taken offline for repairs.

• The error affected the "backbone" network that connects Facebook's computing facilities across the globe, Janardhan said.
• The web monitoring firm Downdetector reported that it was the largest outage they had seen, per Reuters.

What they're saying: "From here on out, our job is to strengthen our testing, drills and overall resilience to make sure events like this happen as rarely as possible," Janardhan said, adding that a review process is underway.

The intrigue: Facebook's products went dark at a moment when the company was already facing headwinds thanks to a whistleblower scandal and changes to its privacy policy that are hurting its ad business. The company was seeing its stocks take a major hit Monday before the apps went dark, Axios' Sara Fisher reports.

Go deeper: Facebook’s very bad few days