title: Azure Blobs - ArgumentNullException when calling UploadFile()
body: <p>I’m getting the following exception when trying to upload a file with the following code:</p>
  
  <pre><code>            string encodedUrl = "videos/Sample.mp4"
              CloudBlockBlob encodedVideoBlob = blobClient.GetBlockBlobReference(encodedUrl);
              Log(string.Format("Got blob reference for {0}", encodedUrl), EventLogEntryType.Information);
              encodedVideoBlob.Properties.ContentType = contentType;
              encodedVideoBlob.Metadata[BlobProperty.Description] = description;
              encodedVideoBlob.UploadFile(localEncodedBlobPath);
  </code></pre>
  
  <p>I see the "Got blob reference" message, so I assume the reference resolves correctly.</p>
  
  <pre><code>Void Run() C:\Inter\Projects\PoC\WorkerRole\WorkerRole.cs (40)
  System.ArgumentNullException: Value cannot be null.
  Parameter name: value
     at Microsoft.WindowsAzure.StorageClient.Tasks.Task`1.get_Result()
     at Microsoft.WindowsAzure.StorageClient.Tasks.Task`1.ExecuteAndWait()
     at Microsoft.WindowsAzure.StorageClient.CloudBlob.UploadFromStream(Stream source, BlobRequestOptions options)
     at Microsoft.WindowsAzure.StorageClient.CloudBlob.UploadFile(String fileName, BlobRequestOptions options)
     at EncoderWorkerRole.WorkerRole.ProcessJobOutput(IJob job, String videoBlobToEncodeUrl) in C:\Inter\Projects\PoC\WorkerRole\WorkerRole.cs:line 144
     at EncoderWorkerRole.WorkerRole.Run() in C:\Inter\Projects\PoC\WorkerRole\WorkerRole.cs:line 40
  </code></pre>
  
  <p>Interestingly, I'm running that same snippet from an on-premises server i.e., outside of Azure and it works correctly.</p>
  
  <p>Ideas welcome, thanks!</p>