vitest-dev/vitest · error · AggregateError

Errors occurred while running tests. For more information, s

Error message

Errors occurred while running tests. For more information, see serialized error.

What it means

AggregateError wrapping every rejected task promise from a single executeTests run. After all task groups (and browser specs) settle via Promise.allSettled, any rejected results are collected and re-thrown together so the caller sees one error carrying all underlying failures (accessible via error.errors). The message is a generic wrapper; the real diagnostics live on the contained errors and the serialized state reported to the UI/reporters.

Source

Thrown at packages/vitest/src/node/pool.ts:231

        if (method === 'collect') {
          promises.push(browserPool.collectTests(browserSpecs))
        }
        else {
          promises.push(browserPool.runTests(browserSpecs))
        }
      }

      const groupResults = await Promise.allSettled(promises)

      results.push(...groupResults)
    }

    const errors = results
      .filter(result => result.status === 'rejected')
      .map(result => result.reason)

    if (errors.length > 0) {
      throw new AggregateError(
        errors,
        'Errors occurred while running tests. For more information, see serialized error.',
      )
    }
  }

  return {
    name: 'default',
    runTests: (files, invalidates) => executeTests('run', files, invalidates),
    collectTests: (files, invalidates) => executeTests('collect', files, invalidates),
    async close() {
      await Promise.all([
        pool.close(),
        browserPool?.close?.(),
        ...ctx.projects.map(project => project.typechecker?.stop()),
      ])
    },
  }

View on GitHub (pinned to d568f8ce37)

Solutions

Inspect the AggregateError.errors array (or the serialized error in the reporter output) to find the root cause of each rejection.
Fix the underlying test/setup/import error reported in the first contained error.
Run a single failing file in isolation (vitest run path/to/file.test.ts) to reproduce without aggregation noise.
Check vitest.state.getUnhandledErrors() / reporter 'unhandled error' output for worker-side context.

Example fix

// before: only see the aggregate message
try {
  await pool.runTests(files)
}
catch (e) {
  console.error(e.message) // 'Errors occurred while running tests...'
}

// after: surface each underlying error
try {
  await pool.runTests(files)
}
catch (e) {
  if (e instanceof AggregateError) {
    for (const cause of e.errors) console.error(cause)
  } else {
    throw e
  }
}

Defensive patterns

Strategy: try-catch

Try / catch

// AggregateError-aware catch: surface each underlying cause
try {
  await vitest.start()
} catch (e) {
  const causes = e instanceof AggregateError ? e.errors : [e]
  for (const cause of causes) console.error(cause)
  process.exitCode = 1
}

Prevention

Treat each AggregateError.errors entry as the real failure to fix, not the wrapper message.
Run the single failing file in isolation to drop aggregation noise.
Wire reporters (junit/html) to capture per-file failures for triage.

When it happens

Trigger: One or more workers/browser tabs reject during pool.runTests or pool.collectTests in createPool (packages/vitest/src/node/pool.ts:221-235). Rejections include worker crashes, test-file load failures, environment setup errors inside a worker, or browser connection failures.

Common situations: A test file throws an uncaught exception during import/evaluation; a worker process exits unexpectedly (OOM, segfault); the browser pool fails to connect; a setup file errors. Anything that rejects a single task promise will surface here.

Related errors

AI-assisted analysis of vitest-dev/vitest@d568f8ce37 (2026-08-03). Data as JSON: /data/errors/0d06eccff3ec5243.json. Report an issue: GitHub.