Support for iOS 4.2.1 ended many years ago. As of May 5, 2025 , WhatsApp officially ceased support for all devices running versions earlier than iOS 15.1.
If you are a collector or using a legacy device for experimental purposes, you can search for archived IPA files on community-driven sites. Use caution, as third-party files can contain malware. Ios 4.2.1 Whatsapp Ipa Download
This is a essential tweak from Cydia that allows the installation of ad-hoc signed IPAs directly on the device. 4. Alternative Workarounds Support for iOS 4