Facebook, Instagram, WhatsApp, and Messenger are back online after the popular social media platforms suffered a massive global outage that lasted almost six hours, affecting tens of millions of users worldwide.
The Facebook-owned platforms all crashed on Monday evening, blocking users from accessing their services.
The California-based company said late on Monday that “the root cause of this outage was a faulty configuration change”, adding that it had "no evidence that user data was compromised as a result of this downtime."
"Our services are now back online and we're actively working to fully return them to regular operations," it said in a statement.
"To all the people and businesses around the world who depend on us, we are sorry for the inconvenience caused by today's outage across our platforms. We've been working as hard as we can to restore access, and our systems are now back up and running.
"We apologize to all those affected, and we're working to understand more about what happened today so we can continue to make our infrastructure more resilient," it said.
All three services are owned by Facebook and could not be accessed over the web or on smartphone apps.
WhatsApp users on both iPhone and Android could not make or receive phone or video calls or send text messages.
While the users of the three social media platforms remained clueless as they repeatedly received error messages for most part of the day, the stocks of Facebook dropped by nearly five per cent.
Earlier, Facebook founder Mark Zuckerberg apologised to those affected by the outage.
"Facebook, Instagram, WhatsApp and Messenger are coming back online now. Sorry for the disruption today -- I know how much you rely on our services to stay connected with the people you care about," he posted on Facebook.
Mike Schroepfer, chief technology officer of Facebook, said on Twitter: “Sincere apologies to everyone impacted by outages of Facebook powered services right now. We are experiencing networking issues and teams are working as fast as possible to debug and restore as fast as possible."
“Facebook services are coming back online now… (It) may take some time to get to 100 per cent. To every small and large business, family, and individual who depends on us, I'm sorry,” Schroepfer said in another tweet.
WhatsApp and Instagram had taken to Twitter to inform their users about the outage.
“We're aware that some people are experiencing issues with WhatsApp at the moment. We're working to get things back to normal and will send an update here as soon as possible. Thanks for your patience!” said the messaging app with more than two billion active users in a tweet.
“Instagram and friends are having a little bit of a hard time right now, and you may be having issues using them. Bear with us, we're on it!” the photo sharing app had tweeted.
The outage of the popular social media platforms came a day before one of its whistleblowers was all set to testify before a Congressional committee.
“It was highly unusual to have so many apps go dark from the world's largest social media company at the same time. More than 3.5 billion people use Facebook and its apps to communicate with one another and conduct business,” The New York Times wrote.
According to The Wall Street Journal, the outage also caused widespread disruptions to Facebook's internal communication tools, including some voice calls and work apps used for calendar appointments and other functions, according to people familiar with the matter.
The company told employees on Monday morning that the cause of the outage was unknown and some staff were using Zoom to remain connected.
Facebook, which has nearly 3 billion monthly users worldwide, is going through one of its worst reputation crises in a fortnight due to revelations by a whistleblower.
Frances Haugen, a former Facebook product engineer, leaked numerous internal documents in the past week, including to The Wall Street Journal.
She further accused the company of "(choosing) profit over the safety" of its users, in an interview broadcast by CBS on Sunday.
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