Old WhatsApp version is obsolete on January 2018, but there's no update on the Play Store WhatsApp shows a notice that the current version is old and obsolete, preventing the user from accessing the chats. It also tells the user to download the latest update.



Tapping the "download" button takes the user to the Play Store. However, there is no option to "update", only "uninstall" and "open".

 

How to force update the WhatsApp app?
Download the APK file directly from the official WhatsApp site and install it.

I have the same issue and this fixed it.