vitest-dev/vitest · error · Error

Don't have access to the "vitest" instance yet. This is a bu

Error message

Don't have access to the "vitest" instance yet. This is a bug in Vitest.

What it means

`PluginHarness.getVitest()` returns the stored `Vitest` instance but throws if `setVitest` was never called (or was called with `undefined`). This harness is an internal seam used to share the Vitest instance with plugins; hitting the error means a code path reached the harness before the core was wired up, which the message itself flags as a Vitest bug rather than user error.

Source

Thrown at packages/vitest/src/node/config/pluginHarness.ts:29

  /**
   * @internal
   */
  public _browserLastPort = defaultBrowserPort

  constructor(
    public logger: Logger = new Logger(),
    public packageInstaller: VitestPackageInstaller = new VitestPackageInstaller(),
  ) {}

  setVitest(vitest: Vitest | undefined): this {
    this.vitest = vitest
    return this
  }

  getVitest(): Vitest {
    if (!this.vitest) {
      throw new Error(`Don't have access to the "vitest" instance yet. This is a bug in Vitest.`)
    }
    return this.vitest
  }
}

View on GitHub (pinned to 1fa9837ec2)

Solutions

1. If this is your code calling the harness, defer the read until a lifecycle hook that runs after the core is ready (e.g. `configResolved`/`buildStart` rather than module top-level).
2. Call `harness.setVitest(vitest)` before invoking `getVitest()` in tests.
3. If you have no custom plugin and hit this, report it as a Vitest bug with the plugin list and stack trace.

Example fix

// before — reads harness before core is set
const vitest = harness.getVitest()

// after — defer to a later hook
export default {
  name: 'my-plugin',
  configureServer(server) {
    const vitest = harness.getVitest() // core is wired up by now
  },
}

// Defer reads until the harness is wired up.
function getVitestOrNull(harness: { vitest?: unknown }) {
  return harness.vitest
}

const v = getVitestOrNull(harness)
if (!v) {
  // skip or queue work instead of calling getVitest()
  return
}

function hasVitest(harness: { vitest?: unknown }): harness is { vitest: NonNullable<typeof harness.vitest> } {
  return harness.vitest != null
}

When it happens

Trigger: A plugin or internal module calls `harness.getVitest()` during construction or config resolution — before `setVitest(server)` runs in the Vitest bootstrap. Also reproducible in tests that instantiate `PluginHarness` directly without calling `setVitest`.

Common situations: Custom plugin that reads the Vitest instance in a hook that fires very early; partial mocks in unit tests; a regression in bootstrap ordering after a Vitest upgrade.

Related errors

• Data was not properly initialized. This is a bug in Vitest.
• Worker state is not found. This is an issue with Vitest. Ple
• stopChunkTrace cannot be called outside of the test file.
• This command can only be called inside a test file.
• provider ${context.provider.name} is not supported

AI-assisted analysis of vitest-dev/vitest@1fa9837ec2 (2026-08-11). Data as JSON: /api/errors/2607e3a6a7d5289d. Report an issue: GitHub.