Millions of phones will soon no longer support WhatsApp due to a major update with the popular messaging app.

Older versions of Android and iOS devices will no longer be able to access the Facebook-owned app from 1 February, while certain Windows phones have already lost support.

WhatsApp said the cull was necessary in order to ensure the security of its users, who are advised to update to the most recent mobile operating system their smartphone supports.

After 31 January, WhatsApp said “some features might stop functioning at any time” because it is no longer actively developing for these operating systems.

“For the following operating systems, you can no longer create new accounts, nor reverify existing accounts,” WhatsApp wrote in a blog post.

“For the best experience, we recommend you use the latest version of iOS [or Android] available for your phone.”

Apple iPhone (iOS)

For Apple devices, any iPhone running iOS 8 or earlier will be culled by WhatsApp at the end of January.

Apple launched iOS 9 in 2015, meaning anyone with an iPhone 6s or newer is safe. Certain older models are able to install iOS 8, though not all. These are the iPhones that came out before the release of iOS 8, together with whether they support the newer software:

Android

The purge will affect any Android phones running a version older than 4.0.3 – also referred to as Ice Cream Sandwich – which was released in 2011.

That means smartphones running Android 2.3.7 (Gingerbread) and earlier will be hit, though this only affects phones more than a decade old.

Even many of those devices launched before 2011 are able to update to the newer operating system, so owners can continue using WhatsApp.​

“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.

“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.”

Android owners can find out which version of the operating system they are using by going to ‘Settings’, then ‘General’, then ‘Software Update’.