Facebook has said that the disruption of its operation was caused by configuration changes on backbone routers. Facebook, in a statement, said its service is now back online.
"Our engineering teams have learned that configuration changes on the backbone routers that coordinate network traffic between our data centers caused issues that interrupted this communication. This disruption to network traffic had a cascading effect on the way our data centers communicate, bringing our services to a halt," the engineers said in a statement on Facebook's website.
"Our services are now back online and we're actively working to fully return them to regular operations. We want to make clear at this time we believe the root cause of this outage was a faulty configuration change," the statement said.
The services went down at about 16:00 GMT with users beginning to gain access to the sites at around 22:00. "Facebook, Instagram, WhatsApp and Messenger are coming back online now. Sorry for the disruption today -- I know how much you rely on our services to stay connected with the people you care about," CEO Mark Zuckerberg informed on Facebook.
According to DownDetector, a website that tracks outages, 40 per cent of WhatsApp users were unable to download the app, 30 per cent had trouble in sending messages and 22 per cent had problems with the web version.
"Apologies to everyone who hasn't been able to use WhatsApp today. We're starting to slowly and carefully get WhatsApp working again. Thank you so much for your patience. We will continue to keep you updated when we have more information to share," WhatsApp tweeted.
(With inputs from agencies)