Mobile messaging service WhatsApp had been hit with an outage, claimed to be its biggest ever, for over three hours on 22 February, inconveniencing users just days after Facebook announced its acquisition for $19bn.
Blaming an error in its network router, the company noted that it was 'experiencing server issues', leading to severe disruption in its service.
WhatsApp founder Jan Koum said: "We are sorry about the downtime."
"It has been our longest and biggest outage in years. It was caused by a network router fault which cascaded into our servers," Koum added.
"We worked with our service provider on resolving the issue and making sure it will not happen again.
Frustrated users took to social media sources, such as blogs and Twitter to report the outage and push out their frustration.
The acquistion was Facebook's most expensive purchase to date, coming less than two years after the social media major raised $16bn from its IPO.
Claiming to be adding a million users daily, five-year-old WhatsApp currently has user base of 450 million across the globe.