mastra-ai/mastra · error · MastraError

EXPERIMENT_TARGET_NOT_FOUND

EXPERIMENT_TARGET_NOT_FOUND

Error message

Target not found: ${args!.targetType} "${args!.targetId}"

What it means

createExperiment resolves the target (agent, workflow, etc.) in the local Mastra registry at creation time so typos fail immediately. If resolveTarget finds nothing for the given targetType/targetId, this error is thrown.

Source

Thrown at packages/core/src/datasets/dataset.ts:676

        text: `targetType and targetId must be provided together (got targetType: ${args?.targetType ?? 'none'}, targetId: ${args?.targetId ?? 'none'})`,
        domain: 'STORAGE',
        category: 'USER',
      });
    }
    if (args?.scorers?.length && !hasTargetType) {
      throw new MastraError({
        id: 'EXPERIMENT_INVALID_TARGET',
        text: 'scorers require a target: without a target Mastra never executes or scores items; submit flat scores via submitExperimentResult instead',
        domain: 'STORAGE',
        category: 'USER',
      });
    }
    // Validate the target exists in this Mastra registry at create time so a
    // typo fails fast instead of failing on the first runExperimentItem call.
    if (hasTargetType) {
      const resolved = await resolveTarget(this.#mastra, args!.targetType!, args!.targetId!);
      if (!resolved) {
        throw new MastraError({
          id: 'EXPERIMENT_TARGET_NOT_FOUND',
          text: `Target not found: ${args!.targetType} "${args!.targetId}"`,
          domain: 'STORAGE',
          category: 'USER',
        });
      }
    }

    const dataset = await datasetsStore.getDatasetById({ id: this.id, filters: this.#scope });
    if (!dataset) {
      throw new MastraError({
        id: 'DATASET_NOT_FOUND',
        text: `Dataset not found: ${this.id}`,
        domain: 'STORAGE',
        category: 'USER',
      });
    }

View on GitHub (pinned to 75dd419e61)

Solutions

1. Register the target (mastra.registerAgent / add workflow) before creating the experiment
2. Fix the targetId spelling to match the registry
3. Ensure createExperiment is called on the same Mastra instance where the target lives

Example fix

// before
await dataset.createExperiment({ targetType: 'agent', targetId: 'summarizer' }); // not registered
// after
mastra.registerAgent({ name: 'summarizer', ... });
await dataset.createExperiment({ targetType: 'agent', targetId: 'summarizer' });

const resolved = await resolveTarget(mastra, args.targetType, args.targetId);
if (!resolved) throw new Error(`Target ${args.targetType} "${args.targetId}" is not registered in this Mastra instance`);

function isRegisteredTarget(t: { targetType: string; targetId: string }, mastra: Mastra): boolean { return resolveTarget(mastra, t.targetType, t.targetId) != null; }

try {
  await dataset.createExperiment(args);
} catch (e) {
  if (isMastraError(e) && e.id === 'EXPERIMENT_TARGET_NOT_FOUND') {
    console.error(`Register ${args.targetType} "${args.targetId}" before creating the experiment`);
  } else throw e;
}

When it happens

Trigger: Calling createExperiment with a targetId that doesn't exist in this Mastra instance, or a targetType with no registered entity of that id.

Common situations: Typo in agent/workflow name; target registered on a different Mastra instance than the Dataset handle uses; renaming an agent without updating experiments; target registered after createExperiment is called.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• EXPERIMENT_NOT_FOUND
• Experiment not found: ${experimentIdA}
• Experiment not found: ${experimentIdB}
• Target not found: ${targetType}/${targetId}
• Version-control repository not found.

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/e0ba4c4308601c4f. Report an issue: GitHub.