version: "1.0.0" name: agents-sdk-dotnet-debugging description: > Use when troubleshooting an agent built with the Microsoft Agents SDK (Microsoft.Agents.Hosting.AspNetCore and related packages) in C# / .NET. Trigger on any of these symptoms: build or C# compile errors, crashes on startup, 401 or auth errors on incoming requests, the bot not responding to messages, appsettings.json configuration problems, Azure AD credential failures (AADSTS errors), port conflicts, or the agent not connecting in Teams or the Agents Playground. Use even if the user doesn't mention the SDK by name — trigger on symptoms like "my bot won't start", "getting 401s", or "bot isn't responding."

Debugging Agents Built with Microsoft Agents SDK (.NET)

Overview

Most agent failures fall into one of three categories: the code doesn't build or start, the configuration is wrong, or the agent isn't reachable. Work through this checklist in order — each step confirms a prerequisite for the next.

Checklist

You MUST create a task for each of these items and complete them in order:

1. Make sure the code builds successfully.
2. Make sure the application starts and runs without crashing.
3. Make sure the application opens a port and listens for incoming requests.
4. Validate the appsettings.json configuration.
5. Validate the bot's credentials against Azure AD.
6. Use the Agents Playground to test the agent end-to-end locally.

1. Build the code

dotnet build

Expected: exits with code 0, no errors. Fix any C# compile errors before continuing.

Common build errors:

• Missing package — dotnet add package Microsoft.Agents.Hosting.AspNetCore
• Namespace not found — wrong using statement; see the agents-sdk-dotnet skill for correct namespaces
• Target framework mismatch — Agents SDK requires .NET 8+; check <TargetFramework> in .csproj

2. Start the application

Run with detailed logging:

dotnet run

Or with verbose logging:

dotnet run --verbosity detailed

To enable debug-level SDK logging, add to appsettings.Development.json:

{
  "Logging": {
    "LogLevel": {
      "Default": "Debug",
      "Microsoft.Agents": "Debug",
      "Microsoft.AspNetCore": "Warning"
    }
  }
}

Watch for crash output. Common startup errors:

• `Unable to resolve service for type 'IStorage'` — missing builder.Services.AddSingleton<IStorage, MemoryStorage>() in Program.cs
• `AddAgentAspNetAuthentication` missing — add builder.Services.AddAgentAspNetAuthentication(builder.Configuration)
• Port already in use — another process is on the port; check with netstat -ano | findstr :3978 (Windows) or lsof -i :3978 (macOS/Linux)
• `InvalidOperationException` on startup — check appsettings.json structure, especially Connections and ConnectionsMap

If the agent starts cleanly, you should see output like:

Now listening on: http://localhost:3978

3. Confirm the agent is reachable

curl -s -o /dev/null -w "%{http_code}" \
  -X POST http://localhost:3978/api/messages \
  -H "Content-Type: application/json" \
  -d '{}'

4. Validate appsettings.json configuration

Configuration mistakes are the most common source of failures. Check each area below.

4a. Confirm the file is being loaded

ASP.NET Core auto-loads appsettings.json and appsettings.{Environment}.json. Check that:

• The file exists in the project root
• It has "Copy to Output Directory": "PreserveNewest" in .csproj or is at the content root
• ASPNETCORE_ENVIRONMENT is set correctly (Development for local dev)

4b. Check the Connections section structure

The SDK requires a specific JSON structure. Common mistakes:

// WRONG — flat format (this is Node.js env var style, not appsettings)
{
  "ClientId": "...",
  "ClientSecret": "...",
  "TenantId": "..."
}
// CORRECT
{
  "Connections": {
    "ServiceConnection": {
      "Settings": {
        "AuthType": "ClientSecret",
        "AuthorityEndpoint": "https://login.microsoftonline.com/<tenantId>",
        "ClientId": "<appId>",
        "ClientSecret": "<secret>",
        "Scopes": ["https://api.botframework.com/.default"]
      }
    }
  }
}

4c. Check ConnectionsMap

If ConnectionsMap is present, it must be a JSON array with proper structure:

// WRONG — object instead of array
"ConnectionsMap": {
  "ServiceUrl": "*",
  "Connection": "ServiceConnection"
}
// CORRECT — array
"ConnectionsMap": [
  {
    "ServiceUrl": "*",
    "Connection": "ServiceConnection"
  }
]

If omitted, the SDK defaults to mapping * to the first connection.

4d. Check TokenValidation section

{
  "TokenValidation": {
    "Enabled": true,
    "Audiences": ["<your-app-id>"],
    "TenantId": "<your-tenant-id>"
  }
}

• Audiences must include your ClientId
• TenantId must match the tenant where the app registration lives
• Set Enabled: false for anonymous local development

4e. Check OAuth handler configuration

If your agent uses user sign-in, verify the AgentApplication:UserAuthorization section:

{
  "AgentApplication": {
    "UserAuthorization": {
      "DefaultHandlerName": "graph",
      "AutoSignin": true,
      "Handlers": {
        "graph": {
          "Settings": {
            "AzureBotOAuthConnectionName": "GraphOAuthConnection",
            "Title": "Sign In",
            "Text": "Please sign in"
          }
        }
      }
    }
  }
}

The handler key (graph) must match the autoSignInHandlers used in route registration. A mismatch causes the sign-in flow to fail silently.

5. Validate bot credentials against Azure AD

Once appsettings.json looks correct, confirm the credentials actually work:

curl -s -X POST \
  "https://login.microsoftonline.com/$tenantId/oauth2/v2.0/token" \
  -d "grant_type=client_credentials\
&client_id=$clientId\
&client_secret=$clientSecret\
&scope=https://api.botframework.com/.default" \
  | jq '{token_type, expires_in, error, error_description}'

A successful response includes access_token. Common errors:

6. Test with Agents Playground

The Agents Playground acts as a mock connector and channel client.

Install:

npm install -g agentsplayground

Run against an anonymous agent:

Start your agent:

dotnet run

In a separate terminal:

agentsplayground -c emulator

Run against an authenticated agent:

agentsplayground -c msteams \
  --client-id <your-app-id> \
  --client-secret <your-secret> \
  --tenant-id <your-tenant-id>

Channel options (-c): msteams, webchat, directline, emulator, agents

If the playground connects but messages don't get responses, the agent is running but a message handler may be missing. Add a fallback handler to confirm:

OnActivity(ActivityTypes.Message, async (ctx, state, ct) =>
{
    await ctx.SendActivityAsync($"Echo: {ctx.Activity.Text}", cancellationToken: ct);
}, rank: RouteRank.Last);

Common Runtime Errors

Validate an OAuth connection name

OAuth connection names can only be tested end-to-end through a real sign-in flow:

Azure Portal → Your Bot Resource → Settings → OAuth Connection Settings → [your connection] → Test Connection

This confirms the connection name matches, the OAuth app has the right scopes, and the redirect URI (https://token.botframework.com/.auth/web/redirect) is registered on the app registration.

Contributing

If you hit a problem this skill couldn't solve, found a workaround, or noticed something wrong or outdated, that's valuable — please help improve this skill for everyone.

Draft a suggested issue title and body based on the conversation, then ask the user to open it at: https://github.com/microsoft/agents/issues/new

A good issue includes:

• What the user was trying to do
• What went wrong (errors, unexpected behavior)
• What worked — including any workaround found during this conversation
• Relevant code or config snippets