A newly published WhatsApp support document shows that WhatsApp has ended support of iOS 9 and earlier, requiring all users to be running iOS 10 or higher.
The requirement limits device compatibility for the end-to-end encrypted messaging service to the iPhone 5 or later, as it is the earliest device that supports iOS 10
According to the support document on the WhatsApp website, these are the new requirements to install the app:
The Facebook-owned messaging system last year dropped support for iOS 8 and lower.
Users that are still running WhatsApp on an unsupported device are strongly recommended to export their entire chat history for importing on to a newer device before the app stops working completely.