This is not the first time that the messaging app has gone down, similar outrages occurred in August and twice in May this year.
Popular messaging app WhatsApp has been hit a major outage disabling 1 billion daily users around the world from using it.
"Whatsappdown" was the top trending item on Twitter in India, which is WhatsApp's biggest market with about 200 million of its billion-plus users.
Along with India, users from most of Europe, Malaysia, Indonesia, China, Saudi Arabia, USA and Sri Lanka complained about the problem.
WhatsApp is yet to issue a statement or reason for the service being unavailable.
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The outage may be an embarrassment for WhatsApp's parent, Facebook, which has this week announced record revenues from advertising.
Twitter and other social media apps were showing complaints by people experiencing the issue.
WhatsApp remained shut for about an hour during which users had trouble updating their profile and other details though tings resumed soon afterwards. This feature has been rolling out to all smartphones using WhatsApp. "This issue has been fixed and we apologise for the inconvenience". Apparently there had been an hour-long outage worldwide.
Many were unable to send or receive texts, images, videos or make calls via the application owned by Facebook.