WhatsApp has gone down for users across the UK, with thousands of people reporting being unable to send or receive messages.
Downdetector, which tracks outages, said more than 12,000 reports of problems had been submitted by 8.30am, with issues first detected just before 8am.
However, the number of users experiencing issues could be much higher due to the way the website collects data.
Many have taken to social media platforms, such as Twitter, to complain that the app is not working.
Users have found that while they can open the app and access their conversations, it is failing to deliver new messages or successfully send any.
A persistent message is showing for many users at the top of the app, saying it is “connecting” to the server, but then appears to fail to do so.
“We’re aware that some people are currently having trouble sending messages, and we’re working to restore WhatsApp for everyone as quickly as possible,” a spokesperson for the platform’s parent company, Meta, said.
WhatsApp is one of the most popular messaging platforms in the UK and around the world, and is estimated to have more than two billion active users globally.