Troubleshooting - Braintrust

No traces appear in Braintrust

Initialize Braintrust with Braintrust.Get() before you create your provider client. Braintrust.Get() sets up the OpenTelemetry pipeline that exports spans to Braintrust, so calls made before it runs are not traced.Make your AI calls on the wrapped client returned by the integration, not the original client:

#skip-compile

var braintrust = Braintrust.Sdk.Braintrust.Get();
var activitySource = braintrust.GetActivitySource();

// Trace calls on `client`, not on a separately constructed client
var client = BraintrustOpenAI.WrapOpenAI(activitySource, apiKey);

No traces when managing your own tracer provider

By default, the SDK manages OpenTelemetry and registers a process-exit hook that flushes traces when your app terminates, so even short-lived processes export correctly with no extra work.If you opt out of auto-management and wire Braintrust into your own TracerProviderBuilder (via OpenTelemetryEnable), that hook isn’t registered. In that case, force a flush before the process exits:

#skip-compile

using Braintrust.Sdk.Trace;

BraintrustTracing.ForceFlush();

ForceFlush returns true when the flush completes within the timeout (10 seconds by default).

Traces are written to the wrong project

Spans route to BRAINTRUST_DEFAULT_PROJECT_NAME, which defaults to default-dotnet-project when unset. Set the project in the environment:

BRAINTRUST_DEFAULT_PROJECT_NAME="My project"

Or pass it through configuration:

#skip-compile

using Braintrust.Sdk;
using Braintrust.Sdk.Config;

var config = BraintrustConfig.Of(("BRAINTRUST_DEFAULT_PROJECT_NAME", "My project"));
var braintrust = Braintrust.Sdk.Braintrust.Get(config);

BRAINTRUST_API_KEY is required error

The SDK looks for your API key in the BRAINTRUST_API_KEY environment variable, then in a .env.braintrust file searched upward from the working directory. Set the variable:

BRAINTRUST_API_KEY="your-api-key"

Create an API key in API key settings if you don’t have one.

Debug setup and API errors

Enable debug logging to surface configuration and export issues, and console trace logging to confirm spans are being created before they’re exported:

BRAINTRUST_DEBUG=true
BRAINTRUST_ENABLE_TRACE_CONSOLE_LOG=true