Facebook, Instagram, WhatsApp reconnecting after nearly six-hour outage

Facebook, Instagram, Messenger and WhatsApp lit up again late on Monday afternoon Eastern time after a nearly six-hour outage that prevented the company’s 3.5 billion users from accessing its social media and messaging services.

Facebook apologized but did not immediately explain what caused the failure, the largest ever tracked by web monitoring group Downdetector.

The outage was the second blow to the social media giant in as many days after a whistleblower on Sunday accused the company of repeatedly prioritizing profit over clamping down on hate speech and misinformation.

As the world flocked to competing apps such as Twitter and TikTok, shares of Facebook fell 4.9%, their biggest daily drop since last November, amid a broader selloff in technology stocks on Monday. Shares rose about half a percent in after-hours trade following resumption of service.

“To every small and large business, family, and individual who depends on us, I’m sorry,” Facebook Chief Technology Officer Mike Schroepfer tweeted, adding that it “may take some time to get to 100%.”

Several Facebook employees who declined to be named said that they believed that the outage was caused by an internal mistake in how internet traffic is routed to its systems. The failures of internal communication tools and other resources that depend on that same network in order to work compounded the error, the employees said.

Security experts said an inadvertent mistake or sabotage by an insider were both plausible.

“Facebook basically locked its keys in its car,” tweeted Jonathan Zittrain, director of Harvard’s Berkman Klein Center for Internet & Society.

Twitter on Monday reported higher-than-normal usage, which led to some issues in people accessing posts and direct messages.

In one of the day’s most popular tweets, video streaming company Netflix shared a meme from its new hit show “Squid Game” captioned “When Instagram & Facebook are down,” that showed a person labeled “Twitter” holding up a character on the verge of falling labeled “everyone.”

Inside a Facebook group for ad buyers, one member wisecracked after service returned that “lots of people searched today ‘how to run google ads for clients.'”

Facebook, which is the world’s largest seller of online ads after Google, was losing about $545,000 in U.S. ad revenue per hour during the outage, according to estimates from ad measurement firm Standard Media Index.

Past downtime at internet companies has had little long-term affect on their revenue growth, however.

Facebook’s services, including consumer apps such as Instagram, workplace tools it sells to businesses and internal programs, went dark noon Eastern time (1600 GMT). Access started to return around 5:45 pm ET.