vitest-dev/vitest · error · TypeError

value must be , received

Error message

${name} value must be ${types.join(' or ')}, received "${receivedType}"

What it means

assertTypes is Vitest's runtime type-validation helper used across config parsing, plugin APIs, and option processing. It checks `typeof value` against an allow-list of type strings and throws a TypeError naming the field, the expected types, and the received type. It is the guard behind many 'X must be Y' configuration errors.

Solutions

Read the error's `name` field to identify which option was rejected, then fix its value type in your config.
Check the Vitest docs or config type definitions for the expected type of that option.
If loading config from JSON/env vars, coerce values to the correct type before passing them in.

Example fix

// before — coverage.thresholds passed as a number instead of object:
coverage: { thresholds: 80 }

// after — correct shape:
coverage: { thresholds: { lines: 80 } }

Defensive patterns

Strategy: validation

Validate before calling

import { assertTypes } from '@vitest/utils/helpers'

// validate config values before passing to Vitest APIs:
assertTypes(myCallback, 'onConsoleLog', ['function','undefined'])

Type guard

function isOfType<T extends string>(value: unknown, ...types: string[]): boolean {
  return types.includes(typeof value)
}

Prevention

Use the vitest.config.ts TypeScript types to catch type mismatches at compile time.
When loading config from env/JSON, coerce values explicitly to the expected type.
Run typecheck (pnpm typecheck) to catch config type errors before runtime.

When it happens

Trigger: Passing a value of the wrong JS type to a Vitest API that internally calls assertTypes — e.g. a non-function to a callback option, a non-string to a path option, or a non-boolean to a flag option.

Common situations: Vitest config (vitest.config.ts) with a mistyped field; passing wrong types to programmatic APIs like createVitest or coverage options; JSON config loaded with coerced string values where booleans/functions were expected.

Related errors

AI-assisted analysis of vitest-dev/vitest@1fa9837ec2 (2026-08-11). Data as JSON: /api/errors/f2f34020398a05ce. Report an issue: GitHub.

Appendix: source

Thrown at packages/utils/src/helpers.ts:47

  const stackTrace = err.stack || ''
  Error.prepareStackTrace = prepareStackTrace
  Error.stackTraceLimit = limit
  return stackTrace
}

export function notNullish<T>(v: T | null | undefined): v is NonNullable<T> {
  return v != null
}

export function assertTypes(
  value: unknown,
  name: string,
  types: string[],
): void {
  const receivedType = typeof value
  const pass = types.includes(receivedType)
  if (!pass) {
    throw new TypeError(
      `${name} value must be ${types.join(' or ')}, received "${receivedType}"`,
    )
  }
}

export function isPrimitive(value: unknown): boolean {
  return (
    value === null || (typeof value !== 'function' && typeof value !== 'object')
  )
}

export function slash(path: string): string {
  return path.replace(/\\/g, '/')
}

const postfixRE = /[?#].*$/
export function cleanUrl(url: string): string {
  return url.replace(postfixRE, '')

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