# Distributed tracing not working on .net \[solution\]

**URL:** <https://discuss.elastic.co/t/distributed-tracing-not-working-on-net-solution/362309>\
**Category:** APM\
**Tags:** dotnet\
**Created:** [July 1, 2024, 5:40pm UTC](https://discuss.elastic.co/t/distributed-tracing-not-working-on-net-solution/362309 "2024-07-01T17:40:24Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![monty241](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/monty241/32/81681_2.png) [@monty241](https://discuss.elastic.co/u/monty241)\
**Post date:** [July 1, 2024, 5:40pm UTC](https://discuss.elastic.co/t/distributed-tracing-not-working-on-net-solution/362309/1 "2024-07-01T17:40:24Z")

</div>

## Summary

`TraceContinuationStrategy` is not a complete successor for `TraceContextIgnoreSampledFalse`. In Transaction.cs, when `TraceContextIgnoreSampledFalse` is true, the ParentId of a distributed transaction will be set to null.

This detaches the local trace from the caller's trace.

For distributed transactions, ensure that `TraceContextIgnoreSampledFalse` is always set to `false`.

## Explanation

Our software runs distributed across a large number of nodes.

Somehow we were unable to instantiate the value of HTTP-header "traceparent" such that it correlated the trace across the nodes.

All [asp.net](http://asp.net) core website instances were initialized using:

```auto
            IApmLogger elasticApmLogger = new ElasticApmLogger();

            AgentComponents agentComponents = new AgentComponents(elasticApmLogger, elasticApmConfig, null);

            Agent.Setup(agentComponents);

            HttpDiagnosticsSubscriber httpDiagnosticsSubscriber = new HttpDiagnosticsSubscriber();
            services.AddElasticApm(httpDiagnosticsSubscriber);

            AspNetCoreDiagnosticSubscriber aspNetCoreDiagnosticSubscriber = new AspNetCoreDiagnosticSubscriber();
            services.AddElasticApm(aspNetCoreDiagnosticSubscriber);

            SqlClientDiagnosticSubscriber sqlClientDiagnosticSubscriber = new SqlClientDiagnosticSubscriber();
            services.AddElasticApm(sqlClientDiagnosticSubscriber);

```

and each one had an individual trace registered.

On the receiving side in the network, the `traceparent` was received by a filter and had a value such as:

```auto
00-e5c1244444312af480bae5db1156ff7d-67f551c7ec652007-01

```

According to [Trace Context](https://www.w3.org/TR/trace-context-1/), the `67f551...007` value is the parent ID to which the local trace should be attached.

However, the outcome of:

```auto
DistributedTracingData distributedTracingData = DistributedTracingData.TryDeserializeFromString(traceParent);

transaction = Agent.Tracer.StartTransaction($"distri-{origin}", ApiConstants.TypeRequest, distributedTracingData);

```

was always that `transaction.ParentId` is null, despite `distributedTracingData.ParentId` being NOT null.

After checking the published source code of `Elastic.Apm.Model.Transaction`, it was found that `TraceContextIgnoreSampledFalse` despited being deprecated with `TraceState` being null, ensures that the `ParentId` is set to null.

```auto
// If TraceContextIgnoreSampledFalse is set and the upstream service is not from our agent (aka no sample rate set)
// ignore the sampled flag and make a new sampling decision.
#pragma warning disable CS0618
if (configuration.TraceContextIgnoreSampledFalse && (distributedTracingData.TraceState == null
#pragma warning restore CS0618
    || (!distributedTracingData.TraceState.SampleRate.HasValue && !distributedTracingData.FlagRecorded)))
  {
    IsSampled = sampler.DecideIfToSample(idBytes);
    _traceState?.SetSampleRate(sampler.Rate);

    // In order to have a root transaction, we also unset the ParentId.
    // This ensures there is a root transaction within elastic.
    ParentId = null;
  }

```

In our case, we have solved it by setting `TraceContextIgnoreSampledFalse` back to the default value `false` and keeping `TraceContinuationStrategy` on `continue`.

After searching a note was found on [HTTP configuration options | APM .NET Agent Reference [1.x] | Elastic](https://www.elastic.co/guide/en/apm/agent/dotnet/current/config-http.html) regarding .NET 5 applications, but it is unclear from the context that this concerns .NET 5 _and newer_ applications. The note might be out-of-date.