CustomExceptionPropertyProvider

Custom Exception Property Provider with Durable Functions (.NET)

.NET | Durable Functions

Description

Demonstrates attaching custom properties to FailureDetails when an activity throws, using the Durable Task Scheduler (DTS) backend.

When an activity throws a BusinessValidationException, the registered IExceptionPropertiesProvider extracts structured fields (string, int, long, date-time, dictionary, list, null) from the exception. The Durable worker propagates those values onto FailureDetails.Properties, which the orchestration observes when it catches the failure — making rich, typed error context available to the orchestrator instead of just a message and stack trace.

Prerequisites

1. .NET 8 SDK
2. Docker (for running the emulator)
3. Azure Functions Core Tools v4

Note: The custom exception property provider requires these minimum versions (the sample references the latest available):

• Microsoft.Azure.Functions.Worker.Extensions.DurableTask >= 1.9.0
• Microsoft.DurableTask.Worker >= 1.16.1 (provides IExceptionPropertiesProvider)
• Microsoft.Azure.Functions.Worker.Extensions.DurableTask.AzureManaged >= 1.2.0 (for the Durable Task Scheduler backend)

Quick Run

1. Start the Durable Task Scheduler emulator:

   docker run -d -p 8080:8080 -p 8082:8082 mcr.microsoft.com/dts/dts-emulator:latest

2. Start the Function app:

   cd samples/durable-functions/dotnet/CustomExceptionPropertyProvider
   func start

3. Start the orchestration:

   curl -X POST http://localhost:7071/api/orchestrators/customException

4. Follow the statusQueryGetUri from the response to see the completed output.

5. View in the dashboard: http://localhost:8082

Expected Output

The orchestration returns the caught FailureDetails, whose Properties carry the custom values supplied by the provider:

{
  "errorType": "CustomExceptionPropertyProvider.BusinessValidationException",
  "errorMessage": "Business logic validation failed",
  "properties": {
    "StringProperty": "validation-error-123",
    "IntProperty": 100,
    "LongProperty": 999999999,
    "DateTimeProperty": "2025-10-15T14:30:00Z",
    "DictionaryProperty": {
      "error_code": "VALIDATION_FAILED",
      "retry_count": 3,
      "is_critical": true
    },
    "ListProperty": ["error1", "error2", 500, null],
    "NullProperty": null
  }
}

How It Works

• BusinessExceptionPropertiesProvider implements Microsoft.DurableTask.Worker.IExceptionPropertiesProvider and is registered as a singleton in Program.cs.
• BusinessActivity throws a BusinessValidationException carrying the structured fields.
• OrchestrationWithCustomException calls the activity, catches the propagated TaskFailedException, and returns ex.FailureDetails — including the custom Properties.

Learn More

• Durable Functions error handling
• Durable Task Scheduler Documentation