Getting exception while uploading video to youtube via wcf services (Google.Apis.YouTube.v3)

Question

Sometime its working fine, but some getting this unknown exception

Object reference not set to an instance of an object. System.Collections.ListDictionaryInternal at BusinessClass.videosInsertRequest_ProgressChanged(IUploadProgress progress) at Google.Apis.Upload.ResumableUpload'1.d__84.MoveNext() --- 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 System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() at...d__102.MoveNext() Object reference not set to an instance of an object. Void videosInsertRequest_ProgressChanged(Google.Apis.Upload.IUploadProgress)

    using (var fileStream = new FileStream(filePath, FileMode.Open))
                {
                    const int KB = 0x400;
                    var minimumChunkSize = 256 * KB;

                    var videosInsertRequest = youtubeService.Videos.Insert(video, "snippet,status", fileStream, "video/*");
                    videosInsertRequest.ProgressChanged += videosInsertRequest_ProgressChanged;
                    videosInsertRequest.ResponseReceived += videosInsertRequest_ResponseReceived;

                    videosInsertRequest.ChunkSize = minimumChunkSize * 4;
                    //videosInsertRequest.Upload();
                    await videosInsertRequest.UploadAsync();
                }

 void videosInsertRequest_ProgressChanged(Google.Apis.Upload.IUploadProgress progress)
        {
            switch (progress.Status)
            {
                case UploadStatus.Uploading:
                    //Console.WriteLine("{0} bytes sent.", progress.BytesSent);
                    break;

                case UploadStatus.Failed:
                    BusinessClass objBusiness = new BusinessClass();
                    objBusiness.writeExceptionLog("videosInsertRequest_ProgressChanged", progress.Exception.InnerException.ToString());

                    //Console.WriteLine("An error prevented the upload from completing.\n{0}", progress.Exception);
                    break;
            }
        }

        void videosInsertRequest_ResponseReceived(Video video)
        {
            getVideoID = video.Id;
            //string getVideoID = video.Id;
            //Console.WriteLine("Video id '{0}' was successfully uploaded.", video.Id);
        }