As of January 1, 2021, WhatsApp will stop working on some smartphone models.
As reported RT, the messaging app will no longer be available on devices not running the iOS 9 or Android 4.0.3 operating systems.
In that sense, this mainly includes the iPhone 4 and all previous models.
Meanwhile, if you have iPhone 4S, iPhone 5, iPhone 5S, iPhone 5C, iPhone 6 and iPhone 6S, what you should do is update to iOS 9 to continue using WhatsApp.
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In the same way, if you have some of the models that will be affected, it is recommended to make a backup copy of the messages in the app, if you do not want to lose the conversations.