Facebook managed to bring down large chunks of the internet last night, thanks to a glitch with Facebook Connect.
Many users attempting to view sites including ther Washington Post, MSNBC.com, Hulu, CNN and Yelp found something else instead: a message reading: 'An error occurred. Please try again later.'
The problem affected users who were logged into Facebook and then used the same browser to log into other sites using their Facebook account. It appears to have been caused by an issue with the Facebook Connect API, triggering sites that use it to redirect users to the Facebook error page. Facebook Connect controls such features as Likes and comments.
The problem appears to have lasted less than an hour, and has been dismissed as insignificant by Facebook. Users could fix the problem by logging out of Facebook - as long as it occurred to them to do so.
"For a short period of time, there was a bug that redirected people logging in with Facebook from third-party sites to Facebook.com," it says in a statement. "The issue was quickly resolved, and Login with Facebook is now working as usual."
What the event does highlight is the near-ubiquity of Facebook these days, and the sheer number of sites that use Facebook Connect - and just how vulnerable they are when something goes wrong.
Advertisers are likely to be sniffy about the the episode, and Facebook may have some more explaining to do.