Meta, which owns WhatsApp, said the problem had been fixed but did not give a reason for the disruption.
People trying to send and receive messages on WhatsApp, which has about two billion users globally, began reporting issues just before 08:00 BST.
More than 12,000 reports were posted within half an hour, according to the service status website Down Detector.
However, by about 10:00 BST service seemed to be returning for many users.
#WhatsApp is working now
— Priya Singh (@priyasi90) October 25, 2022In a statement Meta said the problem had been resolved.
“We know people had trouble sending messages on WhatsApp today,” the statement said.
“We have fixed the issue and apologise for any inconvenience”.
Connection error
As WhatsApp experienced difficulties many people complained on social media that they could not send or receive messages.
Users who tried to use the app on Tuesday morning were faced with a “connecting” message.
The outage is likely have caused significant disruption.
The app, which offers end-to-end encryption for messages, is a popular method of group communication for social, work and parenting activities.
It has even been used, controversially, by government ministers.
According to internet monitoring organisation NetBlocks the outage affected users both in the UK and around the world.
ℹ️ Note: Messaging app WhatsApp is currently experiencing international outages; incident not related to country-level internet disruptions or filtering #WhatsAppDown pic.twitter.com/niy0fKQXGi
— NetBlocks (@netblocks) October 25, 2022There were also reports of issues in Hong Kong, South Africa, Singapore and India – a key market for the platform.
Last year WhatsApp went down as part of of a six-hour outage which also hit Facebook, Oculus and Instagram.
Facebook later said the global problem was caused by a configuration change.
