A screen shot of the popular WhatsApp smartphone application. (© AFP PHOTO / YASUYOSHI CHIBA)

Millions of smartphones with older operating systems are no longer able to run the popular messaging app WhatsApp.

As of Feb. 1, devices that use iPhone iOS 8 and older and Android 2.3.7 are no longer supported by the Facebook-owned company.

Users with these devices have already been unable to create new accounts or re-verify existing accounts.

WhatsApp recommended that users upgrade their software to the latest version to continue using the app and for the “best experience.”

When the decision was first announced in 2017, the company said the move was made to protect their users’ security.

“This was a tough decision for us to make, but the right one in order to give people better ways to keep in touch with friends, family, and loved ones using WhatsApp,” the statement read.

The company said select phones running the Linux-operated KaiOS 2.5.1 and older, including JioPhone and JioPhone 2, will still be supported.

WhatsApp has been gradually withdrawing support from outdated mobile platforms over the past few years in order to “focus our efforts on the mobile platforms the vast majority of people use.”

In 2016, the company ended support for a number of systems, including BlackBerry OS and BlackBerry 10, Nokia S40, Android 2.1 and Android 2.2, Windows Phone 7, and iPhone 3GS/iOS 6.

“While these mobile devices have been an important part of our story, they don't offer the kind of capabilities we need to expand our app's features in the future,” WhatsApp said.