WhatsApp has ended the support for devices that still have old versions of Android. As you can see from their support page. The company now will support devices running:
- Android running OS 4.0.3+
- iPhone running iOS 9+
- Select phones running KaiOS 2.5.1+, including JioPhone and JioPhone 2
For the following operating systems, you can no longer create new accounts, nor reverify existing accounts. However, you’ll be able to continue using WhatsApp on:
- Android versions 2.3.7 and older until February 1, 2020
- iOS 8 and older until February 1, 2020
Also, you’ll no longer be able to use all Windows Phone operating systems after December 31, 2019, and WhatsApp might not be available in the Microsoft Store after July 1, 2019.
So if you use WhatsApp it might be time to upgrade.