As you can see from the notice here, WhatsApp has recently posted an updated notice regarding their support for other operating systems.
That's Android OS newer than 4.0.3, iOS newer than 9, and KaoOS newer than 2.5.1.
The following operating systems will no longer be allowed to create new accounts nor verify existing accounts, and Whatsapp will no longer work on Android versions 2.3.7 and older after February 1, 2020, and iOS 8 and older after February 1, 2020.
You will also no longer be able to use all Windows Phone operating systems after December 31, 2019.
So, if you're using a phone that's unable to be updated to an OS newer than the ones listed, you'll probably want to shift to a newer one if you want to keep using WhatsApp.
This article was first published in Hardware Zone.