vitest-dev/vitest · error · Error

Mock ${id} wasn't resolved. This is probably a Vitest error.

Error message

Mock ${id} wasn't resolved. This is probably a Vitest error. Please, open a new issue with reproduction.

What it means

Thrown by getFactoryModule at packages/mocker/src/browser/mocker.ts:45-47 when a manual mock entry exists in the registry but its cache is falsy, meaning the module was registered but never resolved. Manual mocks must be resolved (via ManualMockedModule.resolve()) before their factory exports can be read.

Source

Thrown at packages/mocker/src/browser/mocker.ts:46

    await Promise.all([...this.queue.values()])
  }

  public async resolveFactoryModule(id: string): Promise<Record<string | symbol, any>> {
    const mock = this.registry.get(id)
    if (!mock || mock.type !== 'manual') {
      throw new Error(`Mock ${id} wasn't registered. This is probably a Vitest error. Please, open a new issue with reproduction.`)
    }
    const result = await mock.resolve()
    return result
  }

  public getFactoryModule(id: string): any {
    const mock = this.registry.get(id)
    if (!mock || mock.type !== 'manual') {
      throw new Error(`Mock ${id} wasn't registered. This is probably a Vitest error. Please, open a new issue with reproduction.`)
    }
    if (!mock.cache) {
      throw new Error(`Mock ${id} wasn't resolved. This is probably a Vitest error. Please, open a new issue with reproduction.`)
    }
    return mock.cache
  }

  public async invalidate(): Promise<void> {
    const ids = Array.from(this.mockedIds)
    if (!ids.length) {
      return
    }
    await this.rpc.invalidate(ids)
    await this.interceptor.invalidate()
    this.registry.clear()
  }

  public async importActual<T>(id: string, importer: string): Promise<T> {
    const resolved = await this.rpc.resolveId(id, importer)
    if (resolved == null) {
      throw new Error(

View on GitHub (pinned to d568f8ce37)

Solutions

1. Ensure resolveFactoryModule(id) is awaited before getFactoryModule(id).
2. Avoid clearing the registry between resolve and read.
3. Report with a reproduction as this is a Vitest-internal lifecycle error.

try {
  vi.mock('./x', factory)
} catch (e) {
  if (e instanceof Error && /wasn't resolved/.test(e.message)) {
    console.error('Vitest internal: manual mock registered but not resolved. Report with reproduction.')
  }
  throw e
}

When it happens

Trigger: getFactoryModule(id) called before resolveFactoryModule(id) (which triggers resolve() and populates cache) was awaited for that id.

Common situations: Internal ordering where the read precedes the resolve; a failed resolve() that left cache unset; reset between resolve and read.

Related errors

• Mock ${id} wasn't registered. This is probably a Vitest erro
• Cannot set serialized manual mock. Define a factory function
• [vitest] Manual mocks require a factory function.
• Cannot find iframe with id ${event.iframeId}
• Cannot spawn child server without a parent dev server.

AI-assisted analysis of vitest-dev/vitest@d568f8ce37 (2026-08-03). Data as JSON: /data/errors/49b82d5a3225ab55.json. Report an issue: GitHub.