Thousands of WhatsApp users in the UK complained that the messaging service isn't working and they weren't able to use the app.
At 8.32am more than 68,000 users reported issues with the app, according to Down Detector.
Of those reporting issues, 55 per cent said they couldn't send messages and 40 per cent said they were having issues connecting with the server.
The Down Detector site included a map showing where the issues are most reported. Large cities of London, Manchester and Cardiff were reporting issues.
Brighton, Glasgow, Nottingham and Birmingham also reported issues
Users across Europe and the rest of the world also reported similar issues using one of the world's most popular messaging platforms.
However, by 10am users reported being able to use the messaging service again after nearly two hours.
A spokesperson for Meta said: "We know people had trouble sending messages on WhatsApp today. We have fixed the issue and apologise for any inconvenience".
WhatsApp is estimated to have more than two billion active users globally.
The app was allowing users to type messages to friends and but when they hit send but the message wasn't getting delivered.
It is unclear what the issue was and what caused it as users started noticing things weren't right at about 8am.
A spokesperson for Meta, the platform's parent company, said: "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."
Many took to Twitter to say they were unable to send messages.
One wrote: "When your WhatsApp is playing up but you come to Twitter and see that everyone else is having the same problem #WhatsAppDown."
It comes as WhatsApp is changing the way it's group chats work, to make them less irritating for users.
If you've ever been in a group chat that is too busy, you'll be familiar with the problem.
Recently, the company started testing maximum group sizes of up to 1,024 people, and trialled a new feature which immediately mutes very large groups when you join them.
The feature was found by the people at WABetaInfo who uncovered the details in the WhatsApp beta trial app.
