Agents SDK Dotnet Debugging Agent Skill

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:

• Make sure the code builds successfully.
• Make sure the application starts and runs without crashing.
• Make sure the application opens a port and listens for incoming requests.
• Validate the appsettings.json configuration.
• Validate the bot's credentials against Azure AD.
• 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 '{}'

| Response | Meaning |

|---|---|

| 401 | Agent is running, auth is active — this is correct for a configured agent |

| 200 | Agent is running with auth disabled (TokenValidation:Enabled = false) — correct for local dev |

| 000 or connection refused | Agent is not running, wrong port, or crashed on startup |

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:

| Error code | Cause |

|---|---|

| AADSTS700016 | ClientId not found in tenant — wrong ID or wrong tenant |

| AADSTS7000215 | Invalid ClientSecret — expired or incorrect |

| AADSTS90002 | TenantId not found |

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

| Error | Cause | Fix |

|---|---|---|

| Unable to resolve service for type 'IStorage' | Missing storage registration | Add builder.Services.AddSingleton<IStorage, MemoryStorage>() |

| MapAgentApplicationEndpoints 404 | Using MapAgentEndpoints (compat) with AgentApplication | Switch to MapAgentApplicationEndpoints |

| MapAgentEndpoints 404 | Using MapAgentApplicationEndpoints with ActivityHandler | Switch to MapAgentEndpoints |

| InvalidOperationException: No agent registered | Missing builder.AddAgent<T>() | Add builder.AddAgent<MyAgent>() |

| 401 on every request | TokenValidation:Enabled is true with no/wrong credentials | Set to false for local dev, or fix credentials |

| System.Text.Json.JsonException on card deserialization | Wrong JSON structure in card content | Validate card JSON separately |

| OAuth sign-in card appears but token exchange fails | Wrong AzureBotOAuthConnectionName | Verify the connection name matches Azure Bot resource OAuth settings |

| Streaming chunks not appearing | Missing EndStreamAsync call | Always call await ctx.StreamingResponse.EndStreamAsync(ct) in a finally block |

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