Here's what Facebook says triggered the massive outage on its apps

Facebook Inc. blamed a global service outage that kept its social media apps offline for much of Monday on a problem with its network configuration, adding that it found no evidence that user data was compromised during the downtime.
 

“This disruption to network traffic had a cascading effect on the way our data centers communicate, bringing our services to a halt,” the company’s engineering team wrote in a blog post Monday night.

The technical issue took Facebook’s core social network, its photo app Instagram and its WhatsApp and Messenger services offline for hours, marking one of the longest and broadest