Benign exceptions - .NET SDK

How to mark an Activity error as benign using the Temporal .NET SDK

When Activities throw errors that are expected or not severe, they can create noise in your logs, metrics, and OpenTelemetry traces, making it harder to identify real issues. By marking these errors as benign, you can exclude them from your observability data while still handling them in your Workflow logic.

To mark an error as benign, set the category parameter to ApplicationErrorCategory.Benign when throwing an ApplicationFailureException.

Benign errors:

• Have Activity failure logs downgraded to DEBUG level
• Do not emit Activity failure metrics
• Do not set the OpenTelemetry failure status to ERROR

using Temporalio.Activities;
using Temporalio.Api.Enums.V1;
using Temporalio.Exceptions;

public class MyActivities
{
    [Activity]
    public async Task<string> MyActivityAsync()
    {
        try
        {
            return await CallExternalServiceAsync();
        }
        catch (Exception e)
        {
            // Mark this error as benign since it's expected
            throw new ApplicationFailureException(
                "Service is down",
                inner: e,
                category: ApplicationErrorCategory.Benign);
        }
    }
}

Use benign exceptions for Activity errors that occur regularly as part of normal operations, such as polling an external service that isn't ready yet, or handling expected transient failures that will be retried.