Facebook said on Thursday that it had repaired a technical error that led to long lapses in service at its various properties, including Instagram, WhatsApp and Messenger.

The interruption lasted nearly 24 hours on some of the services and was the longest in Facebook’s recent history. It was an eye-opening reminder that even the most powerful internet companies, employing the best computer scientists and cutting-edge technology, can still be crippled by human error.
https://www.nytimes.com/2019/03/14/technology/facebook-whatsapp-outage.html