Meituan-Dianping/mpvue · error

Invalid default value for prop "${key}": Props with type Obj

Error message

Invalid default value for prop "${key}": Props with type Object/Array must use a factory function to return the default value.

What it means

Raised in getPropDefaultValue during prop validation when the prop declares a 'default' whose value isObject(def) — i.e. a plain object or array literal. Object/Array defaults are shared by reference across all instances of the component, so one instance mutating the default would leak into every other instance; Vue requires a factory function whose fresh return value is used per instance. The object default is still used (called as-is if a function, otherwise passed through), but the shared-reference hazard remains.

Source

Thrown at src/core/util/props.js:64

  }
  if (process.env.NODE_ENV !== 'production') {
    assertProp(prop, key, value, vm, absent)
  }
  return value
}

/**
 * Get the default value of a prop.
 */
function getPropDefaultValue (vm: ?Component, prop: PropOptions, key: string): any {
  // no default, return undefined
  if (!hasOwn(prop, 'default')) {
    return undefined
  }
  const def = prop.default
  // warn against non-factory defaults for Object & Array
  if (process.env.NODE_ENV !== 'production' && isObject(def)) {
    warn(
      'Invalid default value for prop "' + key + '": ' +
      'Props with type Object/Array must use a factory function ' +
      'to return the default value.',
      vm
    )
  }
  // the raw prop value was also undefined from previous render,
  // return previous default value to avoid unnecessary watcher trigger
  if (vm && vm.$options.propsData &&
    vm.$options.propsData[key] === undefined &&
    vm._props[key] !== undefined
  ) {
    return vm._props[key]
  }
  // call factory function for non-Function types
  // a value is Function if its prototype is function even across different execution context
  return typeof def === 'function' && getType(prop.type) !== 'Function'
    ? def.call(vm)

View on GitHub (pinned to 6c5d78ee04)

Solutions

1. Use a factory function for object/array defaults: props: { items: { type: Array, default: () => [] } } or default() { return { a: 1 } }
2. Scalar defaults (String, Number, Boolean) may stay as plain values
3. Audit shared default objects for in-place mutation; move all mutation to per-instance data copies

When it happens

Trigger: Thrown at src/core/util/props.js:64 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Meituan-Dianping/mpvue@6c5d78ee04 (2026-09-02). Data as JSON: /api/errors/88f32939689854b2. Report an issue: GitHub.