WhatsApp has broken, leaving people unable to chat.
The problems were reported across the world, according to the website Down Detector, and on various platforms including iPhone and Android.
Messages failed to send and the app would not load, according to affected users.
The problems did not appear to be affecting every user of the site, with some able to get onto both the app and its desktop and web versions.
WhatsApp does not maintain a status website to check the availability of its platform or when those will be fixed.
Though it has a public-facing Twitter feed, it has not posted since 2016 and often does not inform users of outages. It also has an official “WhatsApp Status” account that once tweeted about issues and when they would be fixed, but that has not tweeted since 2014 – despite a series of high-profile outages since then.
Though WhatsApp goes offline relatively rarely, even the shortest outage can hit millions of people. Some problems have also happened at unhelpful moments, as when the service broke right in the middle of New Year celebrations.
The issues come amid a difficult time for the platform, which is fighting to keep hoaxes and scams out of its chats.
It has recently limited the number of people who can forward messages, for instance, keeping them to five in the hope it will stop the spread of misinformation.
The Facebook-owned service has also faced questions over its direction, with its founder having left the company amid suggestions that the decision could signal a change in strategy to bring it more in line with its owner.