Many users report a certificate error on older Android versions. To bypass this:
While you can still use WhatsApp on Android 4.4.2, you may encounter some limitations: whatsapp for android 442
Dropping older operating systems allows developers to use modern APIs (Application Programming Interfaces) to build faster, more optimized features for the majority of users. Are There Workarounds to Run WhatsApp on Android 4.4.2? Many users report a certificate error on older