Hi and thanks for the question.
She is on Windows Phone 8.1.
General Store Issue
I believe it is the general issue above, as no app will download (not just WhatsApp), and we get the exact same messages.
I just wanted to point out to Microsoft, that these store issues have a real impact on people's lives, and frustrating given we are all encouraged to use messaging solutions by Microsoft and others.
I appreciate Microsoft does not produce WhatsApp, but it knows that the world uses WhatsApp extensively, and it must also know that WhatsApp will not open if an update fails. You are effectively locked out of the app and your chats.
All my wife wants to do is open the app and "save the chats as email", before we change phones.
WhatsApp Support End
We are aware of the ceasing support, and the total lack of assistance from either Microsoft or WhatsApp.
That is not until mid/end of December, and my Windows Phone 10 is just fine at the moment.
We are shortly moving to Android Phones.
I won't go into the impossibility of migrating Windows WhatsApp messages.dbs files to Android.
You need Interop Tools to unlock the App file system to get the unencrypted version, which is daunting for me, and impossible for your average user. Also, these don't work for my Lumia 950, and the store issues prevent me doing anything for my wife's phone.
In short we are at a dead end, and must accept that our entire chat histories cannot be migrations (and in my wife's care may be lost for ever unless she can re-open WhatsApp).
However, we have accepted that neither Microsoft or WhatsApp care about helping customers move from Windows Phone to Android.
Best Regards
Julian