mastra-ai/mastra · error · MastraError

EXPERIMENT_NOT_FOUND

EXPERIMENT_NOT_FOUND

Error message

Experiment not found: ${experimentId}

What it means

Thrown by the internal #assertExperimentOwnership guard when getExperimentById returns no experiment, or the experiment's datasetId does not match this Dataset handle's id. This ensures a Dataset can only read/update/delete experiments that belong to it (and are within its scope).

Source

Thrown at packages/core/src/datasets/dataset.ts:508

    });
  }

  /**
   * Verify the experiment belongs to this dataset (and, by extension, to the
   * handle's tenancy scope which was enforced when the handle was minted).
   * Throws NOT_FOUND on missing or cross-dataset experiments so cross-tenant
   * mutation via a valid scoped handle + a known foreign experimentId is
   * rejected.
   */
  async #assertExperimentOwnership(experimentId: string): Promise<void> {
    await this.#assertScope();
    const experimentsStore = await this.#getExperimentsStore();
    const experiment = await experimentsStore.getExperimentById({
      id: experimentId,
      filters: this.#scope,
    });
    if (!experiment || experiment.datasetId !== this.id) {
      throw new MastraError({
        id: 'EXPERIMENT_NOT_FOUND',
        text: `Experiment not found: ${experimentId}`,
        domain: 'STORAGE',
        category: 'USER',
      });
    }
  }

  /**
   * Get a specific experiment (run) by ID.
   */
  async getExperiment(args: { experimentId: string }) {
    await this.#assertScope();
    const experimentsStore = await this.#getExperimentsStore();
    const experiment = await experimentsStore.getExperimentById({
      id: args.experimentId,
      filters: this.#scope,
    });

View on GitHub (pinned to 75dd419e61)

Solutions

1. Verify the experimentId exists via the experiments store or listExperiments
2. Confirm the experiment belongs to this dataset (experiment.datasetId === dataset.id)
3. Re-obtain the Dataset handle for the correct dataset that owns the experiment
4. Check that the Dataset handle's scope filters match the environment that created the experiment

Example fix

// before
await wrongDataset.deleteExperiment({ experimentId: id });
// after
const owningDataset = await mastra.getDataset(experiment.datasetId);
await owningDataset.deleteExperiment({ experimentId: id });

const experiment = await experimentsStore.getExperimentById({ id: experimentId, filters: scope });
if (!experiment || experiment.datasetId !== dataset.id) throw new Error(`Experiment ${experimentId} not owned by dataset ${dataset.id}`);

function isOwnedExperiment<T extends { datasetId: string }>(exp: T | undefined | null, datasetId: string): exp is T { return !!exp && exp.datasetId === datasetId; }

try {
  await dataset.deleteExperiment({ experimentId });
} catch (e) {
  if (isMastraError(e) && e.id === 'EXPERIMENT_NOT_FOUND') {
    console.warn(`Experiment ${experimentId} not found for this dataset; skipping`);
  } else throw e;
}

When it happens

Trigger: Calling listExperimentResults, updateExperimentResult, or deleteExperiment with an experimentId that does not exist, is scoped out by filters, or belongs to a different dataset.

Common situations: Copy-pasting an experiment id from another dataset; using an id from a different Mastra instance or storage backend; id typo; experiment was deleted; wrong scope/tenant on the Dataset handle.

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_TARGET_NOT_FOUND
• Experiment not found: ${experimentIdA}
• Experiment not found: ${experimentIdB}
• Version-control repository not found.
• Project repository not found for this organization.

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/dbd9ad1629b82861. Report an issue: GitHub.