WhatsApp stopped working for iPhone 5s
For some reason I cannot use WhatsApp on my iPhone 5s. I thought, the support would end only for iPhone 5 or older generation. Even Google says it should work for iOS 12 and above.
Earlier iPhone models
You will need to contact WhatsApp for help with their software, this is not an Apple product.
Here is a link to their help page.
https://www.whatsapp.com/contact/?subject=messenger
Also you have a very old phone this might be the problem because you can’t update your iOS version.