Facebook Inc blamed a “flawed configuration change” for a nearly six-hour outage Monday that prevented the company’s 3.5 billion users from accessing its social media and messaging services such as WhatsApp , Instagram and Messenger.
The company in a blog post posted Monday night did not say who performed the configuration change and if it was planned.
Several Facebook employees who declined to be named had told Reuters earlier that they believed the outage was caused by an internal error in the way Internet traffic is routed to its systems.
Failures in internal communication tools and other resources that depend on that same network to function compounded the error, employees said. Security experts have said accidental error or sabotage by an insider are both plausible.
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“We want to make it clear at this point that we believe the root cause of this failure was a faulty configuration change,” Facebook said in the blog.
The Facebook outage is the largest ever tracked by the web monitoring group Downdetector.
The blackout 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 cracking down on hate speech and disinformation.
As the world flocked to competing apps like Twitter and TikTok, Facebook shares fell 4.9%, their biggest daily decline since last November, amid a massive sell-off in tech stocks on Monday. Shares rose about half a percent in after-hours trading after service resumed.
“To all the businesses big and small, families and individuals who depend on us, I’m sorry,” tweeted Mike Schroepfer, CTO of Facebook, adding that it “may take a while to reach 100%”.
“Facebook practically locked its keys in his car,” tweeted Jonathan Zittrain, director of the Berkman Klein Center for Internet & Society at Harvard.
Twitter reported above-normal usage on Monday, leading to issues accessing posts and direct messages.
In one of the most popular tweets of the day, video streaming company Netflix shared a meme from its hit new show “Squid Game” captioned “When Instagram and Facebook Are Down,” which showed a person tagged “Twitter” holding a character about to fall labeled “everyone”.
Within a Facebook group for ad buyers, a member scoffed after the service said that “a lot of people have been looking today ‘for’ how to serve Google ads for customers. ‘ in US ad revenue per hour during the outage, according to estimates by ad measurement company Standard Media Index.
However, the internet companies’ past downtime has had little long-term effect on their revenue growth.
Facebook’s services, including consumer apps like Instagram, the work tools it sells to businesses, and internal programs, fell at noon Eastern Time (1600 GMT). Access began to return around 5:45 p.m. ET.
Shortly after the outage began, Facebook acknowledged that users were having difficulty accessing its apps, but did not provide any details on the nature of the problem or indicate the number of users affected.
The error message on the Facebook webpage suggested an error in the Domain Name System (DNS), which allows web addresses to take users to their destinations. A similar outage at cloud company Akamai Technologies Inc shut down several websites in July.
On Sunday, Frances Haugen, who worked as a product manager on Facebook’s civic disinformation team, revealed she was the whistleblower who provided documents supporting a recent Wall Street Journal investigation and a US Senate hearing last week on Instagram’s damage to teenage girls.
Haugen was expected to urge the same Senate subcommittee on Tuesday to regulate the company, which she plans to compare to tobacco companies that have denied for decades that smoking is harmful to health, according to prepared testimony seen by Reuters.