October 6, 2021: -On Monday, Facebook, Instagram, and WhatsApp are once again accessible, more than six hours after users first reported a major outage that took the services offline.

Few the services are not yet fully functioning; for example, some users still report problems posting new content to Instagram.

“To the huge community of people and businesses all over the world who depend on us: we’re sorry,” Facebook said. “We work hard to restore access to our apps and services and are happy to report they are coming back online now. Thank you for bearing with us,” Facebook added. Facebook did not disclose what went wrong.

All three platforms stopped working shortly before noon ET when Facebook’s services’ websites and apps responded with server errors. Reports on DownDetector.com showed the outages appeared widespread, but it was unclear how many users could not access the apps.

ThousandEyes, a network monitoring service owned by Cisco, said in an email that the outage was the result of DNS failure. DNS, short for Domain Name System, is such as phone book for websites.

The outage marked the longest stretch of downtime for Facebook since 2008, when a bug knocked the site offline for about a day, affecting about 80 million users. The platform currently has 3 billion users.

Mike Schroepfer, Facebook’s chief technology officer, apologized in a statement posted to Twitter.

“Sincere apologies to everyone impacted by outages of Facebook-powered services right now,” Schroepfer wrote. “We are experiencing networking issues, and teams are working it faster to debug and restore it faster,” Schroepfer added.

In 2019, a similar outage lasted about an hour, and Facebook blamed a server configuration change for that outage.

The outage comes one day after the whistleblower who leaked private internal research to The Wall Street Journal and Congress revealed herself ahead of an interview with “60 Minutes.” The documents, first reported in a series of Journal stories, revealed that the company’s executives understood the negative impacts of Instagram among younger users and that Facebook’s algorithm enabled the spread of misinformation, among the different things. Facebook shares closed down nearly 5% on the day.