public static async Task GetFileAsync() { var(authResult, message) = await Authentication.AquireTokenAsync(); var httpClient = new HttpClient(); HttpResponseMessage response; var request = new HttpRequestMessage(HttpMethod.Get, MainPage.fileurl); request.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", authResult.AccessToken); response = await httpClient.SendAsync(request); byte[] fileBytes = await response.Content.ReadAsByteArrayAsync(); StorageLibrary videoLibrary = await StorageLibrary.GetLibraryAsync(KnownLibraryId.Videos); string saveFolder = videoLibrary.SaveFolder.Path; string saveFileName = App.Date + "-" + App.StartTime + "-" + App.IBX + "-" + App.Generator + ".xlsx"; saveLocation = saveFolder + "\\" + saveFileName; using (MemoryStream stream = new MemoryStream()) { stream.Write(fileBytes, 0, (int)fileBytes.Length); using (spreadsheetDoc = SpreadsheetDocument.Open(stream, true)) { await Task.Run(() => { File.WriteAllBytes(saveLocation, stream.ToArray()); return(TaskStatus.RanToCompletion); }); } } }