WhatsApp bosses have told users to be patient as they race to find a fix amid a global outage of their popular messaging app.
Social media giants Facebook, Instagram and WhatsApp are all down, according to DownDetector.
More than 46,397 WhatsApp users reported issues using the global instant messaging service from about 4:30pm UK time.
That shot up to 75,600 just before 5pm with a total of 43% of users experiencing issues with the app, with 27% being unable to send messages.
Mark Zuckerberg's social giant Facebook - which owns Instagram and WhatsApp - has also been struggling, with a peak of 58,000 users reporting issues at about 4pm, although the number has now gone down to just under 30,000.
WhatsApp took to Twitter - which appears to be working normally - to say: "We’re aware that some people are experiencing issues with WhatsApp at the moment.
"We’re working to get things back to normal and will send an update here as soon as possible.
"Thanks for your patience!"
And Instagram tweeted to say: "Instagram and friends are having a little bit of a hard time right now, and you may be having issues using them.
"Bear with us, we’re on it! #instagramdown"
It is not known what has caused the outage.
Jake Moore, the former head of digital forensics at Dorset Police and now cybersecurity specialist at global cybersecurity firm, ESET told the Independent.
“Outages are increasing in volume and can often point towards a cyber-attack, but this can add to the confusion early on when we are diagnosing the causes,” he said.
“As we saw with Fastly in the summer, web-blackouts are more often originate from undiscovered software bug or even human error.
“Although these are increasing in frequency and require more failsafes in place, predicting these issues is increasingly more difficult as it was never thought possible before”.
