`OperationCanceledException` not captured with HTTP native instrumentation

[joegoldman2]

Is there any reason why timeouts or requests cancelled by the caller are not reported as error with native HTTP instrumentation? I tested by cancelling the request, with the built-in timeout mechanism (HttpClient.Timeout) and Polly (Microsoft.Extensions.Http.Resilience).

With OpenTelemetry.Instrumentation.Http, Activity.StatusCode and error.type tag are set:

Activity.TraceId:            1bc0f5ddfe12988504745d22f8a57011
Activity.SpanId:             411e2d135daba899
Activity.TraceFlags:         Recorded
Activity.DisplayName:        GET
Activity.Kind:               Client
Activity.StartTime:          2025-06-02T08:11:41.0366467Z
Activity.Duration:           00:00:00.9991566
Activity.Tags:
    http.request.method: GET
    server.address: httpstat.us
    server.port: 443
    url.full: https://httpstat.us/200?sleep=5000
    error.type: System.Threading.Tasks.TaskCanceledException
StatusCode: Error
Activity.StatusDescription:  Task Canceled
Instrumentation scope (ActivitySource):
    Name: System.Net.Http
Resource associated with Activity:
    service.name: basket-api
    host.name: 2d2c402928e7
    deployment.environment: Development

With native instrumentation (manually with ActivityListener or TracerProviderBuilder.AddSource("System.Net.Http")), the span is considered successful as Activity.StatusCode is not set:

Activity.TraceId:            3b94dc1bacb7925e2d06b0255c3a2d64
Activity.SpanId:             7404392518785446
Activity.TraceFlags:         Recorded
Activity.DisplayName:        GET
Activity.Kind:               Client
Activity.StartTime:          2025-06-02T08:15:36.9133316Z
Activity.Duration:           00:00:01.0040950
Activity.Tags:
    http.request.method: GET
    server.address: httpstat.us
    server.port: 443
    url.full: https://httpstat.us/200?sleep=5000
Instrumentation scope (ActivitySource):
    Name: System.Net.Http
Resource associated with Activity:
    service.name: basket-api
    host.name: e2e40c7ea562
    deployment.environment: Development

Looks like this behavior is coming from:

runtime/src/libraries/System.Net.Http/src/System/Net/Http/DiagnosticsHandler.cs

Lines 168 to 174 in 50bf168

	catch (OperationCanceledException)
	{
	taskStatus = TaskStatus.Canceled;
	// we'll report task status in HttpRequestOut.Stop
	throw;
	}

where OperationCanceledException are treated differently and not captured. The finally block doesn't set the error in this case.

[dotnet-policy-service]

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