solidjs/solid · error · Error

Unexpected type ${typeof unwrappedStore} received when initi

Error message

Unexpected type ${typeof unwrappedStore} received when initializing 'createStore'. Expected an object.

What it means

createStore requires initial state that unwraps to an object or function (including arrays). Passing a primitive throws this dev-only error because the store proxy needs a node to wrap; the message includes the actual typeof received to pinpoint the mismatch. For primitive reactive state, createSignal is the intended API.

Source

Thrown at packages/solid/store/src/store.ts:541

  ): void;
}

export type StoreReturn<T> = [get: Store<T>, set: SetStoreFunction<T>];

/**
 * Creates a reactive store that can be read through a proxy object and written with a setter function
 *
 * @description https://docs.solidjs.com/reference/store-utilities/create-store
 */
export function createStore<T extends object = {}>(
  ...[store, options]: {} extends T
    ? [store?: T | Store<T>, options?: { name?: string }]
    : [store: T | Store<T>, options?: { name?: string }]
): StoreReturn<T> {
  const unwrappedStore = unwrap((store || {}) as T);
  const isArray = Array.isArray(unwrappedStore);
  if (IS_DEV && typeof unwrappedStore !== "object" && typeof unwrappedStore !== "function")
    throw new Error(
      `Unexpected type ${typeof unwrappedStore} received when initializing 'createStore'. Expected an object.`
    );
  const wrappedStore = wrap(unwrappedStore);
  if (IS_DEV) DEV!.registerGraph({ value: unwrappedStore, name: options && options.name });
  function setStore(...args: any[]): void {
    batch(() => {
      isArray && args.length === 1
        ? updateArray(unwrappedStore, args[0])
        : updatePath(unwrappedStore, args);
    });
  }

  return [wrappedStore, setStore];
}

View on GitHub (pinned to f47845f9cc)

Solutions

1. Switch primitive state to createSignal: const [v, setV] = createSignal(0)
2. Box the value in the store: createStore({ value: 0 })
3. Validate/normalize initial data before createStore: assert typeof data === 'object'

Example fix

// before
const [count, setCount] = createStore(0); // throws: typeof 'number'

// after
const [count, setCount] = createSignal(0);
// or
const [state, setState] = createStore({ count: 0 });

const isStoreState = (v: unknown): v is object | Function =>
  typeof v === 'object' || typeof v === 'function';
if (!isStoreState(initial)) throw new TypeError('createStore requires object/array initial state');
const [state, setState] = createStore(initial);

const isStoreState = (v: unknown): v is Record<PropertyKey, unknown> | unknown[] =>
  !!v && typeof v === 'object';

When it happens

Trigger: createStore('text'), createStore(0), createStore(true); passing unwrapped JSON like JSON.parse('"hi"'); spreading props or forwarding a field that is sometimes a primitive; defaulting with (store || {}) failing when store is a non-null primitive.

Common situations: Migrating useState/useState-like primitive state to stores during React ports; REST payloads whose root can be a scalar; type errors where Store<T> vs T confusion lets a primitive through.

Related errors

• Unexpected type ${typeof unwrappedStore} received when initi
• Expected the observer to be an object.
• Dispose method must be an explicit argument to createRoot fu
• Cannot mutate a Store directly
• Refusing to set "__proto__" on a store.

AI-assisted analysis of solidjs/solid@f47845f9cc (2026-08-27). Data as JSON: /api/errors/ec29fff3fd374b49. Report an issue: GitHub.