If for some reason you are not able to download WhatsApp from the Play Store. You can get the latest APK and install, that will also updating it your WhatsApp to the latest version.
Possible reasons why you are not able to update WhatsApp?
There can be n number of reasons why you are not able to update your WhatsApp from the Play Store.
One of the reasons could be, your Android device might be considered under the tablet PC, as WhatsApp does not support tablet PCs. You may have gotten lucky at installing WhatsApp for the first time, or maybe the device came with WhatsApp already installed, and now the Google Play Store does not allow updating it.
If this is something you are facing, you can check out this method or workaround to get the latest version of WhatsApp and install it on your Android device.
Another possible reason could be the lack of storage on your Android device, and in that case, it’s not just WhatsApp that you are not able to update, any other App you try to update why play store doesn’t get through, you can install any cache cleaning app, by getting the APK file of the particular app from APKmirror.com or anywhere else, and then try to clean up all the unnecessary files.
The best one is from Google itself, it’s called Google Files Go app. You can install it from the Play Store, but if you are not able to, you can get the file from APKMirror.com
It could also be the issue with Google Play Store app, many have faced this issue, this can also be fixed by doing a clear cache by going to the app info after Google Play Store app, and clearing the cache from the storage section.
So, wrapping it up, there could potentially be three main reasons why WhatsApp is not updating.
1. You have a non-SIM Android device
2. Your Android device is running on low storage
3. There is an issue with the Google Play Store App itself.
If there is any other issue, it might be because of a recent software update on your smartphone, which would only be fixed by either getting another software update from your mobile phone manufacturer, or by the WhatsApp itself.