title: Azure Storage: 403 Server failed to authenticate the request
body: <p>I've search here and in Google but I can't find a solution.</p>
  
  <p>With my C# code I want to read a file from Azure Storage Blob.
  The code (only 6 line) works very well in another project (Windows 8.1 Universal App) but not in my new Windows 10 UWP App.</p>
  
  <p>This is my code:</p>
  
  <pre><code>CloudStorageAccount storageAccount = CloudStorageAccount.Parse(azureConnectionString);
  CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
  CloudBlobContainer container = blobClient.GetContainerReference("container-name");
  
  CloudBlob b1 = container.GetBlobReference("27.76914.json");
  StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync("stefano1.json", CreationCollisionOption.ReplaceExisting);
  await b1.DownloadToFileAsync(file);
  </code></pre>
  
  <p><strong>The Exception:</strong></p>
  
  <blockquote>
    <p>Server failed to authenticate the request. Make sure the value of
    Authorization header is formed correctly including the signature.</p>
  </blockquote>
  
  <p><strong>Using Fiddler4 I found this error on message 403:</strong></p>
  
  <blockquote>
    <p>The MAC signature found in the HTTP request 'R2t9hKsyXf470HF2LNP8T+M2nci0ddE/ojQ0r4UVjJQ=' is not the same as any computed signature</p>
  </blockquote>
  
  <p><strong>My attempts:</strong></p>
  
  <ol>
  <li>The application works the first time (file downloaded). The second time I get the Exception.</li>
  <li>If I change the requested file name: the application works the first time (file downloaded). The second time I get the Exception.</li>
  <li>The next day I get immediately the same exception (at first run)</li>
  <li>Also if I delete bin and obj folders I get the error</li>
  <li>If I create another application and try to download the same file (same as point 1), it works the first time, but not the second.</li>
  <li>In a Console Application all works well.</li>
  </ol>
  
  <p><strong>This is the Fiddler4 Raw Request</strong> (where ***** is my Azure Storage Account Name):</p>
  
  <pre><code>GET https://*****.blob.core.windows.net/container-name/27.76914.json HTTP/1.1
  x-ms-client-request-id: accee7e7-646d-417a-b734-1591cbc16a8d
  x-ms-date: Thu, 03 Sep 2015 06:31:37 GMT
  x-ms-version: 2015-02-21
  User-Agent: WA-Storage/5.0.2 (Windows Runtime)
  Authorization: SharedKey *****:R2t9hKsyXf470HF2LNP8T+M2nci0ddE/ojQ0r4UVjJQ=
  Host: *****.blob.core.windows.net
  If-Modified-Since: Sun, 30 Aug 2015 18:52:41 GMT
  If-None-Match: "0x8D2B16C2ED82C4A"
  Connection: Keep-Alive
  </code></pre>
  
  <p>Thank you!</p>