Facebook briefly broke parts of the internet yesterday as millions of users were unable to access websites.
Facebook plugins found on thousands of web pages, which allow people to share or recommend articles turned out to be broken.
Those visiting websites including Fairfax news sites, BuzzFeed, The Huffington Post, The Washington Post, CNN and more were instead directed to a Facebook error page with a message saying "An error occurred. Please try again later".
According to the Atlantic Wire, Facebook has only offered a cryptic comment about what happened, even though the problem appears to be fixed.
A Facebook spokesman admitted that for a short period of time there was a bug that redirected people logging in with Facebook from third party sites to Facebook.com. The problem was quickly resolved, and Login with Facebook is now working as usual.
The case is being seen as one of the dangers when people relying on other sites for core functions; many sites even use Facebook Connect whereby instead of creating a new user account users can simply log in with their Facebook details.