Social media users were in disarray when Facebook and its affiliated apps, including Instagram and WhatsApp, crashed for several hours on Oct. 4.

Users noticed error messages on Facebook apps at around 11:40 a.m.and the tech giant announced a fix and apologized six hours later, according to The New York Times.

In an official statement, the company noted that the cause of the outage was due to changes in configurations to routers in their data centers. This meant that the update to their routers led to disruptions within Facebook’s internal systems, which elongated the outage and prevented employees from reaching the routers, according to NPR.

“We want to make it clear that there was no malicious activity behind this outage — its root cause was a faulty configuration change on our end,” the official Facebook post read. “We also have no evidence that user data was compromised as a result of this downtime.”
This outage is the company’s biggest since March 2019. Before that, the company’s largest shutdown was in 2008 when it had only 80 million users at the time, according to The Verge.

More than 3.5 billion users were affected by the latest shutdown. Social media and commerce apps’ operations, including Messenger, Instagram and WhatsApp, were also halted, as well as other apps and services where Facebook is used to sign in to them.

Facebook’s own app, as well as its affiliates like Messenger and WhatsApp, are some of the main modes of international communication. Countries such as India, Brazil and Mexico who rely on Facebook’s services for messaging and commerce were devastated by the shutdown, according to The Guardian.

“They are often the backbone of communication in these countries. Small businesses and informal economies in particular rely on Facebook’s services,” Callum Sillars, a social media expert at Ampere Analysis, said to The Guardian.