Unfortunately, there is no fix. You will be forced to upgrade to an incompatible version. At that point, your device has truly reached end-of-life for WhatsApp.
:Go to Settings > Security > check the box for Unknown Sources . This allows you to install apps from outside the Google Play Store. Download Whatsapp For Android Version 4.4.4
As of writing this article, WhatsApp on Android 4.4.4 is in . That means: Unfortunately, there is no fix