If you are researching this for a project or looking to revive an old device, here is the current state of the "paperwork" on this topic: Server-Side Killswitches
: Unlike many offline apps, WhatsApp checks its version against the server. Even if you successfully sideload a version like whatsapp ipa for ios 9.3.5 download
The logic behind searching for a WhatsApp IPA for iOS 9.3.5 is simple: If I can find the file for the last version of WhatsApp that worked on iOS 9, surely I can install it manually? If you are researching this for a project
While there isn't a formal academic "paper" titled "WhatsApp IPA for iOS 9.3.5 Download," Apps must be "signed" by a valid Apple Developer certificate
iOS does not allow you to simply drag and drop an IPA file onto a device. Apps must be "signed" by a valid Apple Developer certificate. To run an old WhatsApp IPA, you must re-sign it with a personal certificate, which often requires sideloading software.
Meta announces server shutdowns for legacy versions months in advance. Once they deprecate the API, you will see a message: "Please update to the latest version of WhatsApp to continue using this app." At that point, there is no fix.