Using WhatsApp on unsupported software carries significant risks, including potential loss of access to your messages and vulnerabilities to security threats. If the device cannot be updated to at least Android 5.0, the most reliable way to continue using the service safely is to use a device that meets the current official system requirements. This ensures that the account remains protected by the latest encryption and feature updates provided by the platform. About supported operating systems | WhatsApp Help Center
or newer. While historical versions of WhatsApp previously supported API 16 (Android 4.1), those versions now fail to connect to Meta’s servers for number verification and messaging. 1. Current Support Status Minimum Requirement download whatsapp for android version 4.1.1