WhatsApp no longer supports Windows Phone
WhatsApp is culling some of the older operating systems it runs on. The latest one to get axed is Windows Phone. The messaging app no longer supports Microsoft's mobile platform. And older OSes like Android 2.3.7 and iOS 8 or older will not get support after February 1, 2020. Users will no longer be able to create new accounts or verify existing ones on these platforms. You will not be able to transfer your chat history from one platform to another, so you might need to export your chat history as an email attachment if you want access to them. But it would be best if you did so before the deadline.
Source: Engadget