Whatsapp has gone down on what is believed to be a worldwide scale - leaving millions of users without a connection. The popular messaging app is reported to be malfunctioning, and won't allow users to connect to their chat messages.
Hundreds of people from different countries have already taken to Twitter to flag the problem.
Users in Europe, South America, Africa and the US are all thought to have been affected for the last hour, according to Down Detector.
A spokesperson for the company has told Reuters that Whatsapp is aware of the problem is trying to fix it.
Over a billion people are believed to rely on the Facebook-owned app for messaging.
It's a free app that lets users chat and call each other for no charge, as well as sending links, videos and pictures.
When it launched, the instant messaging service - which connects via 3G or wireless networks - was only available to smartphone users.
The messaging app is also reportedly working on a feature that could let users unsend embarrassing messages after they have been sent.
As long as the double-blue tick wasn't showing, users could reportedly press and hold on a message to bring up the options to edit or revoke the message.
But it is not clear if, or when, the update will be rolled out.
But in January, it was announced that the service will be available on desktop computer users too.