The WhatsApp messaging service will no longer work on millions of smartphones from February 1.
Android and iPhone devices that only support outdated operating systems will no longer be able to run the Facebook-owned application.
WhatsApp said the move was necessary to protect the safety of its users.
Smartphones using Android 2.3.7 and earlier and iPhone iOS 8 or earlier are the ones affected by the update.
The operating systems for which WhatsApp removes support are legacy operating systems, which are no longer updated or installed on new devices.
Most users can simply update their operating systems to continue using the messaging service.
However, some devices, such as the iPhone 4, which only supports iOS 7, will no longer be compatible with the app.
“WhatsApp clearly had no choice but to guarantee the security of its service, but it faces the difficult side effect that the application is no longer compatible with older smartphones,” said Ben Wood. , analyst at CCS Insight.
“This is likely to have a disproportionate impact on the long tail of its users, especially in growing markets where there is a high proportion of older devices.
WhatsApp, which was one of the most downloaded apps of the decade, first warned users that these changes would happen in 2017.
“It was a difficult decision for us, but the right one to give people better ways to stay in touch with friends, family and loved ones using WhatsApp, “said a spokesperson for the company.
It is the latest in a series of moves after the messaging app removed support for many devices in 2016, then all Windows phones on December 31, 2019.