Unauthorized Access exception in OpenStreamForWriteAsync Windows Phone 8.1

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serialization

authorization

, +

I'm trying to save some informations into a file in the ApplicationData.Current.LocalFolder this way:

private async Task WriteRecentScores(List<ScoreRecord> list)
    {
        try
        {
            var serializer = new DataContractJsonSerializer(typeof(List<ScoreRecord>));
            using (var stream = await ApplicationData.Current.LocalFolder.OpenStreamForWriteAsync(
                          RECENTSCOREFILE,
                          CreationCollisionOption.ReplaceExisting))
            {
                serializer.WriteObject(stream, list);
            }
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex.Message);
            Debug.WriteLine(ex.StackTrace);
        }
    }

but I get an Unauthorized Access exception when reaching OpenStreamForWriteAsync.

RECENTSCOREFILE="score.json" is a file created when launching the app for the very first time (I'm using the FailIfExists option), here's the code:

private async void CreateFile()
    {
        try
        {
            StorageFolder folder = ApplicationData.Current.LocalFolder;
            StorageFile file = await folder.CreateFileAsync(RECENTSCOREFILE, CreationCollisionOption.FailIfExists);
        }
        catch (Exception) { }

        return;
    }

The funny thing is that I tried to launch the app both in the emulator and in my phone and it seems that it throws the exception only when running on the phone.

I figured out that it works only the first time I write the file, but how can I solve this?