Azure Bot Framework Emulator Error - System.ArgumentNullException: Value cannot be null

Question

I am needing some help. I am new at developing in Azure's Bot Framework, creating my first chatbot some weeks ago using a QnA KB. In any case, I managed to create the bot in Azure's portal and it is working perfectly. But I need to do some alterations and tests in Bot Framework Emulator (using V4) and, to do so, download and run locally my bot.

I made the download of my bot's .zip file following Azure's instructions and initialized it using Visual Studio 2017 as my IDE. When I hit the button "debug", though, the program tries to connect to localhost:3984.

using Autofac;
using System.Web.Http;
using System.Configuration;
using System.Reflection;
using Microsoft.Bot.Builder.Azure;
using Microsoft.Bot.Builder.Dialogs;
using Microsoft.Bot.Builder.Dialogs.Internals;
using Microsoft.Bot.Connector;

namespace SimpleEchoBot
{
    public class WebApiApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            // Bot Storage: This is a great spot to register the private state storage for your bot. 
            // We provide adapters for Azure Table, CosmosDb, SQL Azure, or you can implement your own!
            // For samples and documentation, see: https://github.com/Microsoft/BotBuilder-Azure

            Conversation.UpdateContainer(
                builder =>
                {
                    builder.RegisterModule(new AzureModule(Assembly.GetExecutingAssembly()));

                    // Using Azure Table Storage

                    var store = new TableBotDataStore(ConfigurationManager.AppSettings["AzureWebJobsStorage"]); // requires Microsoft.BotBuilder.Azure Nuget package 

                    // To use CosmosDb or InMemory storage instead of the default table storage, uncomment the corresponding line below
                    // var store = new DocumentDbBotDataStore("cosmos db uri", "cosmos db key"); // requires Microsoft.BotBuilder.Azure Nuget package 
                    // var store = new InMemoryDataStore(); // volatile in-memory store

                    builder.Register(c => store)
                        .Keyed>(AzureModule.Key_DataStore)
                        .AsSelf()
                        .SingleInstance();

                });
            GlobalConfiguration.Configure(WebApiConfig.Register);
        }
    }
}

In matter of seconds, though, the following line of code returns the error System.ArgumentNullException: 'Value cannot be null. Arg_ParamName_Name':

var store = new TableBotDataStore(ConfigurationManager.AppSettings["AzureWebJobsStorage"]); // requires Microsoft.BotBuilder.Azure Nuget package

As a consequence, I am unable to test my bot in the Bot Framework Emulator. Since I am really new with C#, could anyone give me a hand at solving this?

EDIT: Here is my web.config part of the code, just removing sensitive data:

EDIT 2: Some screenshots of the issue so far:

EDIT 3: Trying to solve "Please set QnAKnowledgebaseId, QnAAuthKey and QnAEndpointHostName (if applicable) in App Settings. Learn how to get them at https://aka.ms/qnaabssetup.". Basic QnAMakerDialog.cs so far (the first instances of qnaAuthKey, qnaKBId and endpointHostName had values attributed to them, but I erased them at here for safety):

using System;
using System.Threading;
using System.Threading.Tasks;

using Microsoft.Bot.Builder.Azure;
using Microsoft.Bot.Builder.Dialogs;
using Microsoft.Bot.Builder.CognitiveServices.QnAMaker;
using Microsoft.Bot.Connector;
using System.Configuration;
namespace Microsoft.Bot.Sample.QnABot
{
    [Serializable]
    public class RootDialog : IDialog

Ashwin Kumar · Accepted Answer

As the error mentions, the problem here is that, AzureWebJobsStorage cannot be found in the web.config file. To fix your problem, navigate to your bot in azure portal and click on app settings from the left blade. There you will find a setting with the key AzureWebJobsStorage. Copy the value of the setting and paste that in the web.config file as :

Update:

To answer your further question posted in the comments,

I am redirected to a blank page in my browser, with the address localhost:3984 and a text where you can read QnABot Template, followed by some links

Indicates that the bot is working perfectly now and it is in fact the expected behavior. To test the bot locally, you need to use Bot Emulator. Follow the steps mentioned in the link and test the bot. Also you could go through the bot framework links, as that will give you more clarity on Microsoft Bot Framework.

Update 2:

As per your screenshots posted, I think you have changed the Global.asax file. The code for registering TableBotDataStore should be exactly

var store = new TableBotDataStore(ConfigurationManager.AppSettings["AzureWebJobsStorage"]);

No change at all to this.

Secondly as mentioned by Fei Han :

The Utils.GetAppSetting(string key) method is for bots running on Azure, if you’d like to run your bot application on local and access settings from your web.config file, you can use ConfigurationManager.AppSettings[“your_key”] to replace Utils.GetAppSetting(“your_key”) in your QnAMakerDialog.

The second screenshots shows that you still have Utils.GetAppSetting(“your_key”) in your code. Replace it to :

var qnaKBId = ConfigurationManager.AppSettings["QnAKnowledgebaseId"];

and so on for other places as well.

Azure Bot Framework Emulator Error - System.ArgumentNullException: Value cannot be null

Answers (2)

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