diff --git a/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.AnnotatedSandwichBot/AnnotatedSandwich.cs b/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.AnnotatedSandwichBot/AnnotatedSandwich.cs
index a8a594e64..8e7ab6384 100644
--- a/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.AnnotatedSandwichBot/AnnotatedSandwich.cs
+++ b/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.AnnotatedSandwichBot/AnnotatedSandwich.cs
@@ -300,7 +300,8 @@ public static IForm<SandwichOrder> BuildLocalizedForm()
                         .Field(nameof(Toppings),
                             validate: async (state, value) =>
                             {
-                                var values = ((List<object>)value).OfType<ToppingOptions>();
+                                // CXuesong: Fix for Microsoft/BotBuilder#2780
+                                var values = ((List<object>)value)?.OfType<ToppingOptions>();
                                 var result = new ValidateResult { IsValid = true, Value = values };
                                 if (values != null && values.Contains(ToppingOptions.Everything))
                                 {
diff --git a/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.EchoBot/Controllers/MessagesController.cs b/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.EchoBot/Controllers/MessagesController.cs
index 2aaf63208..90d46f8bb 100644
--- a/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.EchoBot/Controllers/MessagesController.cs
+++ b/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.EchoBot/Controllers/MessagesController.cs
@@ -2,6 +2,7 @@
 using System.Linq;
 using System.Net;
 using System.Net.Http;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 
 using Microsoft.AspNetCore.Authorization;
@@ -12,6 +13,7 @@
 using Microsoft.Bot.Builder.Dialogs;
 using Microsoft.Bot.Builder.Dialogs.Internals;
 using Autofac;
+using Microsoft.Bot.Builder.Scorables;
 using Microsoft.Extensions.Logging;
 
 namespace Microsoft.Bot.Sample.AspNetCore.Echo.Controllers
@@ -22,6 +24,22 @@ public class MessagesController : Controller
         private readonly Conversation conversation;
         private readonly ILogger<MessagesController> logger;
 
+        public static void ConfigureConversation(Conversation conversation)
+        {
+            conversation.UpdateContainer(builder =>
+            {
+                var scorable = Actions
+                    .Bind(async (IBotToUser botToUser, IMessageActivity message) =>
+                    {
+                        await botToUser.PostAsync("polo");
+                    })
+                    .When(new Regex("marco"))
+                    .Normalize();
+
+                builder.RegisterInstance(scorable).AsImplementedInterfaces().SingleInstance();
+            });
+        }
+
         public MessagesController(Conversation conversation, ILoggerFactory loggerFactory)
         {
             if (conversation == null) throw new ArgumentNullException(nameof(conversation));
diff --git a/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.EchoBot/Startup.cs b/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.EchoBot/Startup.cs
index bd197654e..a0c3a3afa 100644
--- a/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.EchoBot/Startup.cs
+++ b/CSharp/Samples/Microsoft.Bot.Sample.AspNetCore.EchoBot/Startup.cs
@@ -9,6 +9,7 @@
 using Microsoft.Extensions.Logging;
 using Microsoft.Bot.Connector;
 using Microsoft.Bot.Builder.Dialogs;
+using Microsoft.Bot.Sample.AspNetCore.Echo.Controllers;
 
 namespace Microsoft.Bot.Sample.AspNetCore.Echo
 {
@@ -34,7 +35,12 @@ public void ConfigureServices(IServiceCollection services)
             // Authentication for Microsoft Bot Framework.
             services.AddSingleton(_ => new MicrosoftAppCredentials(Configuration,
                 _.GetService<ILoggerFactory>().CreateLogger<MicrosoftAppCredentials>()));
-            services.AddSingleton<Conversation>();
+            services.AddSingleton(_ =>
+            {
+                var c = new Conversation(_.GetService<MicrosoftAppCredentials>());
+                MessagesController.ConfigureConversation(c);
+                return c;
+            });
 
             // Add framework services.
             services.AddMvc(options =>