Behavior of Redux When Dispatching Undefined or Invalid Actions
If you dispatch an action with an undefined or invalid type in Redux Toolkit (or Redux in general), the store will ignore it because every reducer relies on a valid action.type to determine how the state should change.
If
action.typeisundefined, Redux will throw an error since action objects must have a stringtypeproperty.If the
typedoesn’t match any reducer case, the store simply returns the current state — no changes occur.Middleware like thunks or loggers might still receive the action, but it won’t update the state unless explicitly handled.
To prevent these issues, always use auto-generated action creators from createSlice() or createAction(). These utilities guarantee correctly structured action objects with valid types.