mastra-ai/mastra · error · Error

Storage not configured. Configure storage in Mastra instance

Error message

Storage not configured. Configure storage in Mastra instance.

What it means

compareExperiments compares score data of two experiments, which requires a configured storage backend on the Mastra instance. If mastra.getStorage() returns undefined, no storage was configured and comparison cannot proceed.

Source

Thrown at packages/core/src/datasets/experiment/analytics/compare.ts:62

 *   thresholds: {
 *     'accuracy': { value: 0.05, direction: 'higher-is-better' },
 *     'latency': { value: 100, direction: 'lower-is-better' },
 *   },
 * });
 *
 * if (result.hasRegression) {
 *   console.log('Quality regression detected!');
 * }
 * ```
 */
export async function compareExperiments(mastra: Mastra, config: CompareExperimentsConfig): Promise<ComparisonResult> {
  const { experimentIdA, experimentIdB, thresholds = {} } = config;
  const warnings: string[] = [];

  // 1. Get storage
  const storage = mastra.getStorage();
  if (!storage) {
    throw new Error('Storage not configured. Configure storage in Mastra instance.');
  }

  const experimentsStore = await storage.getStore('experiments');
  const scoresStore = await storage.getStore('scores');

  if (!experimentsStore) {
    throw new Error('ExperimentsStorage not configured.');
  }
  if (!scoresStore) {
    throw new Error('ScoresStorage not configured.');
  }

  // 2. Load both experiments
  const [experimentA, experimentB] = await Promise.all([
    experimentsStore.getExperimentById({ id: experimentIdA }),
    experimentsStore.getExperimentById({ id: experimentIdB }),
  ]);

View on GitHub (pinned to 75dd419e61)

Solutions

Configure storage on the Mastra instance, e.g. new Mastra({ storage: new MastraStorage(...) })
Check mastra.getStorage() before calling compareExperiments and surface a clear config error
Verify the storage dependency/package is installed and imported correctly
Ensure env vars controlling storage config are set in the runtime environment

Example fix

// before
const mastra = new Mastra({ agents: {...} }); // no storage
compareExperiments({ mastra, ... });
// after
const mastra = new Mastra({ agents: {...}, storage: new LibSQLStore({ url: process.env.DB_URL }) });

Defensive patterns

Strategy: validation

Validate before calling

const storage = mastra.getStorage();
if (!storage) throw new Error('Configure storage on the Mastra instance before comparing experiments');

Type guard

function hasStorage(mastra) { return typeof mastra.getStorage === 'function' && mastra.getStorage() != null; }

Try / catch

try {
  const report = await compareExperiments({ mastra, config });
} catch (e) {
  if (e instanceof Error && /Storage not configured/i.test(e.message)) {
    // reconfigure Mastra with a storage backend and retry
  } else throw e;
}

Prevention

Always pass storage when constructing Mastra if you use datasets/experiments
Assert storage presence once at app startup, not at point of use
Keep storage config env-driven and validated on boot

When it happens

Trigger: Calling compareExperiments(config) with a Mastra instance constructed without a storage option, or before storage is attached.

Common situations: Forgetting to pass storage in new Mastra({...}); running analytics in a test/dev environment with in-memory-only setup; storage config gated behind env vars that are unset in the deployment.

Understand the failure class

Background: "environment variable is not set" and "Missing keys in environment" errors: what missing required env var messages mean and how to fix them — this error's family across 28 libraries.

Related errors

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/444b7e4c68918c28. Report an issue: GitHub.