The WhatsApp messaging application owned by Facebook went offline and was unavailable for many users across the UK, Europe and the rest of the world for more than two hours.
Problems began at around 8:30pm (BST) on Wednesday (3 May) and were felt in London, Manchester and Leeds, as well as across much of the Netherlands, Paris, Munich, Milan, Berlin and Vienna.
Techradar reported that WhatsApp had got the messaging service back up and running.
In a company statement, it said: "Earlier today, WhatsApp users in all parts of the world were unable to access WhatsApp for a few hours," a spokesperson said. "We have now fixed the issue and apologise for the inconvenience."
There is still no word on what caused the outage.
Problems logging into the app were reported by users in South Africa, South America, Mexico and the United States.
Users, including those at IBTimes UK, found WhatsApp difficult to connect to, with messages appearing several minutes after they were sent, or in some cases not arriving at all. At the time of writing, the app is not working when connected over both Wi-Fi and the cellular network.
The app was last offline on New Year's Eve.
Naturally, disgruntled WhatsApp users soon flocked to Twitter to vent their anger and poke fun at the widespread outage.
WhatsApp remained offline at 10:40pm, over an hour after the problems began, with the 'Connecting...' message appearing continuously at the top of the conversations page. We will update this article if and when the company releases a statement about the outage.
Service was resumed around two hours later and is now (8:00 the next morning) running normally.
WhatsApp said in a statement: "Earlier today, WhatsApp users in all parts of the world were unable to access WhatsApp for a few hours. We have now fixed the issue and apologise for the inconvenience."