Facebook has said that a “server configuration change” was to blame for the worst outage in its history.
It said it had “triggered a cascading series of issues” for its platforms, including WhatsApp and Instagram.
The disruption, which lasted for more than 14 hours, left most of its products inaccessible around the globe.
It took the social network giant a full day from when the problems began to offer any explanation.
It added that everything was now back to normal.