title: Error uploading items with Walmart marketplace API feed
body: <p>I am trying to upload items with Walmart marketplace APIs(Bulk Create Item)
  but always get a response as 500 Internal server error. Any Ideas?
  the other Api functions are okay but not this func..
  Actually Others are using Method is "application/xml" but this is using "multipart/form-data;"</p>
  
  <p>Note that the XML strings/example in the code below are taken from <a href="https://developer.walmartapis.com/#the-item-object" rel="nofollow noreferrer"><code>https://developer.walmartapis.com/#the-item-object</code></a> and then I changed IDs property.</p>
  
  <pre><code>     public bool RequestUpdateItem()
          {
                      string strBaseUrl = string.Format("https://marketplace.walmartapis.com/v2/feeds?feedType=item");
                      string strRequestMethod = "POST";
                      WalmartSignature Signature = new WalmartSignature(consumerId, privateEncodedStr, strBaseUrl, strRequestMethod);
  
                      string strSignature = string.Empty;
                      HttpWebRequest httpWebRequest = null;
                      HttpWebResponse httpWebResponse = null;
                      WalmartOrderModel orderModel = new WalmartOrderModel();
                      StringBuilder strBuilder = new StringBuilder();
                      bool bReturnValue = false;
                      try
                      {
                          strSignature = Signature.GetSignature(null);   // null -&gt; generate timestamp
                          httpWebRequest = (HttpWebRequest)WebRequest.Create(strBaseUrl);
                          httpWebRequest.Method = strRequestMethod;
                          httpWebRequest.Accept = "application/xml";
                          httpWebRequest.ContentType = "multipart/form-data;";
  
                          httpWebRequest.Headers.Add("WM_SVC.NAME", "Walmart Marketplace");
                          httpWebRequest.Headers.Add("WM_SEC.AUTH_SIGNATURE", strSignature);
                          httpWebRequest.Headers.Add("WM_CONSUMER.ID", Signature.ConsumerId);
                          httpWebRequest.Headers.Add("WM_SEC.TIMESTAMP", Signature.TimeStamp);
                          httpWebRequest.Headers.Add("WM_QOS.CORRELATION_ID", Guid.NewGuid().ToString());
  
  
  
                          string strRequestBody =
          @"&lt;?xml version=""1.0"" encoding=""UTF-8""?&gt;
          &lt;MPItemFeed xmlns=""http://walmart.com/"" xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xsi:schemaLocation=""http://walmart.com/MPItem.xsd""&gt;
          &lt;MPItemFeedHeader&gt;
          &lt;version&gt;2.1&lt;/version&gt;
          &lt;requestId&gt;333pecEl55nics&lt;/requestId&gt;
          &lt;requestBatchId&gt;333ecElect55cs38&lt;/requestBatchId&gt;
          &lt;/MPItemFeedHeader&gt;   
          &lt;MPItem&gt;
          &lt;sku&gt;BDK72wsd44f&lt;/sku&gt;
          &lt;Product&gt;
          &lt;productName&gt;QVS&lt;/productName&gt;
          &lt;longDescription&gt;QVS&lt;/longDescription&gt;
          &lt;shelfDescription&gt;QVS&lt;/shelfDescription&gt;
          &lt;shortDescription&gt;QVS&lt;/shortDescription&gt;
          &lt;mainImage&gt;
          &lt;mainImageUrl&gt;http://images.antonline.com/img-main/500/037229400328.jpg&lt;/mainImageUrl&gt;
          &lt;/mainImage&gt;
          &lt;productIdentifiers&gt;
          &lt;productIdentifier&gt;
          &lt;productIdType&gt;UPC&lt;/productIdType&gt;
          &lt;productId&gt;220740171234&lt;/productId&gt;
          &lt;/productIdentifier&gt;
          &lt;/productIdentifiers&gt;
          &lt;productTaxCode&gt;2038710&lt;/productTaxCode&gt;
          &lt;additionalProductAttributes&gt;
          &lt;additionalProductAttribute&gt;
          &lt;productAttributeName&gt;product_id_override&lt;/productAttributeName&gt;
          &lt;productAttributeValue&gt;true&lt;/productAttributeValue&gt;
          &lt;/additionalProductAttribute&gt;
          &lt;/additionalProductAttributes&gt;
          &lt;Electronics&gt;
          &lt;brand&gt;QVS&lt;/brand&gt;
          &lt;ElectronicsCables&gt;
          &lt;/ElectronicsCables&gt;
          &lt;/Electronics&gt;
          &lt;/Product&gt;
          &lt;price&gt;
          &lt;currency&gt;USD&lt;/currency&gt;
          &lt;amount&gt;99.29&lt;/amount&gt;
          &lt;/price&gt;
          &lt;shippingWeight&gt;
          &lt;value&gt;0.12&lt;/value&gt;
          &lt;unit&gt;LB&lt;/unit&gt;
          &lt;/shippingWeight&gt;
          &lt;/MPItem&gt;
          &lt;/MPItemFeed&gt;";
  
  
                          MemoryStream stream = new MemoryStream();
                          StreamWriter writer = new StreamWriter(stream);
                          writer.Write(strRequestBody);
                          writer.Flush();
                          stream.Position = 0;
  
                          httpWebRequest.ContentLength = stream.Length;
  
  
                          using (Stream requestStream = httpWebRequest.GetRequestStream())
                          {
                              stream.CopyTo(requestStream);
                              //requestStream.Write(stream, 0, stream.Length);
  
                              httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
                              if (httpWebResponse.StatusCode == HttpStatusCode.OK)
                              {
                                  Stream streamResponse = httpWebResponse.GetResponseStream();
                                  var responseResult = XDocument.Load(streamResponse);
                              }
                          }
  
                      }
                      catch (Exception ex)
                      {
                          Console.WriteLine("RequestUpdateItem(): " + ex);
                      }
  
                      return bReturnValue;
                  }
  </code></pre>