Social media giant Facebook apologised this evening after its second outage in a week and third in a month.
Millions of users were greeted with a message reading "sorry something went wrong" just after 9pm.
The site, which claims to have 1.23 billion monthly users, displayed an error message to users who were trying to log on.
Users also could not access Facebook from mobile phones.
The service started being restored by 9.30pm.
"We are currently restoring Facebook services that people had trouble accessing earlier today due to a configuration," Facebook spokesman Jay Nancarrow told the media.