Xamarin Android - After user updates app, it crash

Question

So Im getting reports that after some users updated the app it wouldn't load. They could fix this easily by uninstalling the app and installing it again from the app store.

Firstly I would like to know if there's a way to prevent this? And Whats the logical way to explain whats happening?

I have Googled similar terms and come across apps like Facebook and Instagram which also inform the user to uninstall and reinstall that app. Im unable to replicate this and no ones reporting the crashes to the store. They just send an email saying its not working.