Microsoft.WindowsAzure.Storage.StorageException：远程服务器返回错误：（404）Not Found

Question

I am receiving this error in my worker role:

 Microsoft.WindowsAzure.Storage.StorageException: The remote server returned an error: (404) Not Found. ---> System.Net.WebException: The remote server returned an error: (404) Not Found.     at System.Net.HttpWebRequest.GetResponse()     at Microsoft.WindowsAzure.Storage.Core.Executor.Executor.ExecuteSync[T](StorageCommandBase`1 cmd, IRetryPolicy policy, OperationContext operationContext)     --- End of inner exception stack trace ---     at Microsoft.WindowsAzure.Storage.Core.Executor.Executor.ExecuteSync[T](StorageCommandBase`1 cmd, IRetryPolicy policy, OperationContext operationContext)     at Microsoft.WindowsAzure.Storage.Queue.CloudQueue.DeleteMessage(String messageId, String popReceipt, QueueRequestOptions options, OperationContext operationContext)     at Microsoft.WindowsAzure.Storage.Queue.CloudQueue.DeleteMessage(CloudQueueMessage message, QueueRequestOptions options, OperationContext operationContext)     at CloudCartConnector.TaskRole2.WorkerRole.ExecuteTask() in C:\a\src\CCC\Source\CloudCartConnector.TaskRole2\WorkerRole.cs:line 101  Request Information  RequestID:7a7c08ec-0003-0059-6d7b-2d118f000000  RequestDate:Thu, 03 Dec 2015 03:33:11 GMT  StatusMessage:The specified queue does not exist.  ErrorCode:QueueNotFound  

If there was an exception in the on start method, would this cause a worker role to fail to run? Should I enter a try catch statement in the on start method and just return base.OnStart()? If my storage accounts becomes unavailable, due to a MS upgrade or a server going down, is the try catch the best?

    public override bool OnStart()
    {
        ServicePointManager.DefaultConnectionLimit = 12;
        // Retrieve storage account from connection string.
        CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
            CloudConfigurationManager.GetSetting("StorageConnectionString"));

        // Create the queue client.
        CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

        // Retrieve a reference to a queue.
        queue = queueClient.GetQueueReference("taskqueue");

        return base.OnStart();
    }

Below this code, I execute a task. Should I say if the queue is null, just return?

public string GetTasks()
    {


                CloudQueueMessage cloudQueueMessasge = new CloudQueueMessage(message);
                queue.AddMessage(cloudQueueMessasge, new TimeSpan(0, 30, 0));                
        }
        catch (Exception ex)
        {
            return ex.ToString();

        }
    }

Answer 1

You should have a try...catch block in your OnStart method.

try{
      CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
      CloudConfigurationManager.GetSetting("StorageConnectionString"));

      // Create the queue client.
      CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

            // Retrieve a reference to a queue.
       queue = queueClient.GetQueueReference("taskqueue");
}
catch(Microsoft.WindowsAzure.Storage.StorageException e)
{
   // Exception Handling & Logging
   // Return false for OnStart
}

You should also check if queue is null in your GetTasks() method to prevent throwing potential and unnecessary NullReferenceException.