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All of Facebook Inc.’s social media platforms became inaccessible for users starting about 11:45 a.m. EDT today as a result of a yet-unexplained outage.

The hours-long outage affected Facebook’s namesake social network, as well as Instagram, WhatsApp and Messenger. Users have reportedly encountered multiple types of error messages across the services, including “Sorry, something went wrong” and “5xx Server Error,” among others. Facebook’s Oculus Quest virtual reality headsets are affected as well.

Update: As of about 6:15 p.m. EDT, the site was back up, but the web infrastructure and security firm CloudFlare said some services will take longer to be restored.

Even the company’s Workplace team collaboration platform is said to be experiencing issues. As a result, employees of the social network reportedly have limited access to some work-related tools. The outage is also affecting a number of third-party applications that integrate with Facebook’s login system.

“We’re aware that some people are having trouble accessing our apps and products. We’re working to get things back to normal as quickly as possible, and we apologize for any inconvenience,” Facebook said in a statement. The company has not yet shared any technical details on the outage. 

According to cybersecurity journalist Brian Krebs, Facebook’s Domain Name System infrastructure encountered a malfunction this morning. The Domain Name System, or DNS, helps establish connections between users’ browsers and websites. When a user enters a URL into a browser, the backend DNS infrastructure finds the servers that host the corresponding website.

Confirmed: The DNS records that tell systems how to find https://t.co/qHzVq2Mr4E or https://t.co/JoIPxXI9GI got withdrawn this morning from the global routing tables. Can you imagine working at FB right now, when your email no longer works & all your internal FB-based tools fail?

— briankrebs (@briankrebs) October 4, 2021

It’s unclear whether the issue with Facebook’s DNS infrastructure is what led to today’s outage, or if the root cause is another system. 

Separately, Cloudflare Inc. Senior Vice President Dane Knecht noted that Facebook’s Border Gateway Protocol or BGP routers are experiencing issues as well. BGP, like DNS, is a foundational component of the internet, though it has a different function. The technology is responsible for finding the fastest network path through which data can travel between a user’s browser and a website.

. @Facebook DNS and other services are down. It appears their BGP routes have been withdrawn from the internet. @Cloudflare 1.1.1.1 started seeing high failure in last 20mins.

— Dane Knecht (@dok2001) October 4, 2021

Facebook, Instagram, WhatsApp and Messenger previously experienced a brief outage in April. The social network attributed the incident to a configuration change but didn’t share more detailed technical information. 

Photo: Eston Bond/Flickr