What does error message "You need the official WhatsApp to use this account Using an app other than the official WhatsApp has privacy and security risks Use WhatsApp to register or log back in." mean and how can I solve and fix it.
WhatsApp
*. Clear Data and Cache.
*. Uninstall and Reinstall again.
*. This solution has worked for a lot of people so you should try it too:
Go to https://www.apkmirror.com/apk/whatsapp-inc/whatsapp/ and download latest version.
Open the APK file on your phone and install it. tell your phone that the unknown source you are trying to download this from is safe and that you want to proceed.
This should fix the problem.