File retrieved by SharedStorageAccessManager.CopySharedFileAsync is empty

Question

I have a really strange problem in my Silverlight WP 8.1 app, which some users reported to me, but which I cannot reproduce myself.
My app registers a file handler to open e-mail attachments. The file handler is working so far, however some users report that the files are empty in the app or contain the string "NIL". I tried a lot of debugging in the emulator and on my phone,
but I have not been able to reproduce this. Therefore, I added some "client-side debugging facilities" into the app. My code in the file handler looks like this:
var storageFile = await SharedStorageAccessManager.CopySharedFileAsync(ApplicationData.Current.LocalFolder, localFileName, NameCollisionOption.ReplaceExisting, fileToken);
var fileProps = await storageFile.GetBasicPropertiesAsync();
using (var ras = await storageFile.OpenReadAsync())
using (Stream s = ras.AsStreamForRead()) {
var sr = new StreamReader(s);
var fileContent = sr.ReadToEnd();
My first assumption that I encounter some line break issues. However, users having the issue report that the file size in the app (I display fileProps.Size in case of an error) is zero, while the mail app shows several KBs. I told users to install a text
reader app and try to open it with this app, and from what I hear the multi-KB attachments are also empty in the text reader app. Users also reported, that the effect does not occur with all files, so the problem seems to occur only in certain combinations
of devices and files.
From what I see, my code is OK - and it seems to work in most cases. What can I do about this problem? And as a first step, how can I further debug it? Getting the file properties seems the most I can do with the storage API ...
Thanks in advance,
Christoph

Answer 1

Hmmm.
Well there are two possibilities I'm thinking here.
1)
The file is somehow messed up on their phone but in a very strange way since it can be forwarded OK.
This seems rather unlikely.
3)
The files are fine on the users' phones and user error or whatever means they could open them in a text reader but aren't.
I would refactor async calls into callbacks.
I would also consider saving some info to isolated storage and implement some sort of error reporting service.
Serialise file data like size and perhaps the first so many bytes to xml.
Give them a button or something allows them to send last transmission data to your service.
Supporting end consumer apps is a bit of a challenge without data.
Something we've been discussing recently since I'm ( unusually ) working on something consumers will use.
Hope that helps.
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