FacebookWe are sorry for the error. the mass outageThat meant billions of users couldn’t access Facebook, Instagram and WhatsApp for many hours.

Santosh Janardhan is Facebook’s vice president of infrastructure. He said, “To all people and businesses throughout the world that depend on us. We are sorry for today’s inconvenience across our platforms.” blogpostLate Monday

Janardhan stated that the outage caused by configuration changes to the backbone routers, which made it impossible for users to refresh their feeds and send messages. He did not specify what these changes were.

He said that the changes created “issues” which disrupted the flow traffic among routers at Facebook’s global data centers.

Janardhan stated that the disruption in network traffic caused a ripple effect on how data centers communicate and brought an end to our services.

Facebook, Instagram, WhatsApp and WhatsApp both stopped operating shortly before noon ET. This was because the Facebook apps and websites were experiencing server error responses.

Just after 7 p.m. ET: Six hours and forty minutes after both platforms were offline, Facebook CEO Mark Zuckerberg announced on Facebook, “Facebook. Instagram. WhatsApp. Messenger. We are back online.”

He added: “Sorry for the disruption today – I know how much you rely on our services to stay connected with the people you care about.”

This outage was the longest period of Facebook downtime since 2008. In 2008, Facebook suffered from a bug that caused the site to go offline for around a day. It affected approximately 80 million people. It currently hosts around 3Billion users.

A similar outage occurred in 2019, lasting about an hour. Facebook blamed the server configuration changes for this outage.

The interruption occurred one day following the disclosure of private research by a whistleblower to Congress and The Wall Street Journal revealed herselfInterview with 60 Minutes. These documents were first published in Journal stories. They revealed that company executives knew the adverse effects of Instagram on younger users, and that Facebook’s algorithm allowed for misinformation to spread, among other things.

Facebook shares closed downThey were almost 5% higher Monday, but they rose over 1% on Tuesday in pre-market trades.  

— Additional reporting by CNBC’s Samantha Subin.