reduxjs/react-redux · error

Unexpected value for ${methodName} in connect.

Error message

Unexpected value for ${methodName} in connect.

What it means

Before connect builds its selectors, verifySubselectors checks that mapState/mapDispatch selectors are truthy and, if they are objects (impure form), that they declare a dependsOnOwnProps property. A falsy selector means connect cannot compute props, so it throws immediately during connect setup.

Source

Thrown at src/connect/verifySubselectors.ts:5

import warning from '../utils/warning'

function verify(selector: unknown, methodName: string): void {
  if (!selector) {
    throw new Error(`Unexpected value for ${methodName} in connect.`)
  } else if (
    methodName === 'mapStateToProps' ||
    methodName === 'mapDispatchToProps'
  ) {
    if (!Object.prototype.hasOwnProperty.call(selector, 'dependsOnOwnProps')) {
      warning(
        `The selector for ${methodName} of connect did not specify a value for dependsOnOwnProps.`,
      )
    }
  }
}

export default function verifySubselectors(
  mapStateToProps: unknown,
  mapDispatchToProps: unknown,
  mergeProps: unknown,
): void {
  verify(mapStateToProps, 'mapStateToProps')

View on GitHub (pinned to 16f1a91eb2)

Solutions

1. Log the selector just before connect() to confirm it is defined and truthy
2. Break circular imports: move the selector into its own module that does not import back into the component file
3. For object-form mapState/mapDispatch, ensure the object literal (not undefined) is passed

Example fix

// before (circular import leaves selector undefined)
import { mapStateToProps } from './selectors'
export default connect(mapStateToProps)(Comp)
// after
import { mapStateToProps } from './pureSelectors' // no cycle
export default connect(mapStateToProps)(Comp)

if (!mapStateToProps) throw new Error('connect: mapStateToProps is falsy (undefined import or circular dependency?)');
if (typeof mapStateToProps === 'object' && !('dependsOnOwnProps' in mapStateToProps)) {
  mapStateToProps.dependsOnOwnProps = false;
}

function isSelector(v: unknown): v is ((state: any, ownProps?: any) => any) {
  return typeof v === 'function';
}

try {
  Connected = connect(mapStateToProps, mapDispatchToProps)(Component)
} catch (e) {
  if (e.message.includes('Unexpected value for')) {
    console.error('Selector undefined — check for circular imports')
  }
  throw e
}

When it happens

Trigger: Passing undefined/null/false as mapStateToProps or mapDispatchToProps to connect(), e.g. when a module's export failed to initialize (circular import) or when a helper that was supposed to generate the selector returned undefined.

Common situations: Circular dependency where mapState is undefined at module-eval time, conditional export logic that skips the selector, or refactoring that deleted the selector but left connect(mapState, ...) in place.

Related errors

• Invalid value of type ${typeof arg} for ${name} argument whe
• You must pass a component to the function returned by connec
• You must pass a valid React context consumer as `props.conte
• could not find react-redux context value; please ensure the
• You must pass a selector to useSelector

AI-assisted analysis of reduxjs/react-redux@16f1a91eb2 (2026-08-31). Data as JSON: /api/errors/27efd50062c6d3e4. Report an issue: GitHub.