title: InvalidBlockList error while uploading CloudBlockBlob in parallel
body: <p>I have an application that uploads the CloudBlockBlob in parallel using following method</p>
  
  <p><a href="https://msdn.microsoft.com/en-us/library/dn434979.aspx" rel="nofollow">UploadFromStreamAsync MSDN Documentation</a></p>
  
  <pre><code>CloudBlockBlob.UploadFromStreamAsync Method (Stream, AccessCondition, BlobRequestOptions, OperationContext)
  </code></pre>
  
  <p>Sometimes I have observed that file upload is erroring due to exception mentioned below.</p>
  
  <pre><code>Microsoft.WindowsAzure.Storage.StorageException: The remote server returned an error: (400) Bad Request. ---&gt; System.Net.WebException: The remote server returned an error: (400) Bad Request.
     at Microsoft.WindowsAzure.Storage.Shared.Protocol.HttpResponseParsers.ProcessExpectedStatusCodeNoException[T](HttpStatusCode expectedStatusCode, HttpStatusCode actualStatusCode, T retVal, StorageCommandBase`1 cmd, Exception ex)
     at Microsoft.WindowsAzure.Storage.Blob.CloudBlockBlob.&lt;PutBlockListImpl&gt;b__33(RESTCommand`1 cmd, HttpWebResponse resp, Exception ex, OperationContext ctx)
     at Microsoft.WindowsAzure.Storage.Core.Executor.Executor.EndGetResponse[T](IAsyncResult getResponseResult)
     --- End of inner exception stack trace ---
     at Microsoft.WindowsAzure.Storage.Core.Util.StorageAsyncResult`1.End()
     at Microsoft.WindowsAzure.Storage.Core.Util.AsyncExtensions.&lt;&gt;c__DisplayClass4.&lt;CreateCallbackVoid&gt;b__3(IAsyncResult ar)
  --- End of stack trace from previous location where exception was thrown ---
     at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
     at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
     at WKHMR.SSR.Common.Azure.Storage.AzureBlobStorage.&lt;UploadFileAsync&gt;d__32.MoveNext()
  
  
  StatusMessage:The specified block list is invalid.
  
  ErrorCode:InvalidBlockList
  </code></pre>
  
  <p>Anyone know what could be the possible cause of this error? and How to fix it?</p>