System.InvalidOperation错误 - 我做错了什么？

Question

我有这个代码向订阅者发送短信通知（大约60,000个订阅者）我一直收到错误 System.InvalidOperationException 没有数据时读取的尝试无效。我做错了什么代码在

之下

var sw = new Stopwatch();
            sw.Start();

            var networkSettings = ops.GetNetworkSettings().ToDictionary(x => x.NetworkID, x => x.BillingURL);
            var serviceIds = serviceRepository.All.Where(x=>x.Status);
            //var blastMsgs = new Dictionary<int, Blast>();

            var currTime = DateTime.Now.TimeOfDay;
            foreach (var item in serviceIds)
            {
                var termTime = item.TermTime;
                var termTimeCeiling = currTime.Add(TimeSpan.FromMinutes(15));
                var termTimeFloor = currTime.Add(TimeSpan.FromMinutes(-15));

                if (termTime < termTimeFloor || termTime > termTimeCeiling) continue;

                var activeEntry = entryRepository.GetMessage(item.ServiceId);

                if (activeEntry == null) continue;

                var accounts = accountRepository.SubscribersByServ(item.ServiceId);
                log.Debug("entry is: "+activeEntry.Msg);
                log.Debug("num of accounts: "+accounts.Count());
                log.Debug("service id is: "+item.ServiceId);
                var options = new ParallelOptions {MaxDegreeOfParallelism = 200};

                var count = 0;
                Parallel.ForEach(accounts, options, x =>
                                                        {
                                                            Thread.CurrentThread.IsBackground = false;
                                                            lock (log)
                                                            {
                                                                var msg = new OutboundMessage
                                                                              {
                                                                                  Message = activeEntry.Msg,
                                                                                  PhoneNumber = x.PhoneNumber,
                                                                                  SenderId = item.Sender,
                                                                                  NetworkId = x.NetworkId
                                                                              };

                                                                if (!ops.DoBilling(msg, item.CampaignId.ToString(), networkSettings)) return;
                                                                accountRepository.UpdateAccount(x.SubscriberId);                                                                  
                                                                Interlocked.Increment(ref count);
                                                                log.Debug("current bill count is: "+count);
                                                            }

                                                        });

                entryRepository.UpdateMessage(activeEntry.MessageId);
                log.Debug("Service Id: " + item.CampaignId);
                log.Debug("Bill count is " + count);
            }

            sw.Stop();
            log.Debug("total bill time: "+sw.Elapsed.TotalMinutes+" minutes");