Reported that there are problems with the application, there are over 1.2 billion users globally, first appeared around 20 pm GMT.
WhatsApp said in a brief statement that it was “aware of the problem and working to fix it as soon as possible”.
At around 2230 GMT, most users have reported that they can send and receive messages again.
But according to both the DownDetector and Outage Report, some continue to have problems.
There is no comment from WhatsApp about what’s causing the problem, nor how extensive it is.
A second statement from the company, released after the service was reinstated, said:
“Earlier, WhatsApp users around the world were unable to access WhatsApp for several hours.
“We have now fixed the problem and apologized for the inconvenience.”
Dave Anderson, a digital experience expert at Dynatrace, told the BBC that he believed that updates to the application could cause problems.
“WhatsApp sends a new version of the app to stores every few days, and they could push code changes every hour to get ready for that,” he said.
“Every development is risky.”
It only takes one line of code and the application will fail.
“Banks can only release a new version of the app every quarter because they can not take that risk.”
WhatsApp, he said, will be under greater pressure to keep updating and adding new features.
WhatsApp v Snapchat
WhatsApp was sold to Facebook in 2014.
The same functionality as Snapchat and Instagram Stories, which allows users to create a post containing words, images or videos, disappears after 24 hours.
Snapchat, which has been in existence since September 2011, is said to have about 160 million users.
Instagram announced last month that about 200 million people use the Story feature every day.
By: Anna Lee