React troubleshooting
Fix provider boundaries, slot error isolation, and test scheduling warnings.
Slot error renders the route fallback instead of the slot fallback
Symptom A sidebar, header, modal, or other slot throws during render and the route/provider error fallback replaces a larger part of the page than expected.
Cause
<Slot /> was rendered without errorFallback, so slot errors intentionally bubble to the existing route/provider error boundary.
Fix
Pass a slot-local fallback. Use errorFallback={null} to render nothing, an inline function for custom UI, or a fallback component.
<Slot name="modal" errorFallback={null} />
<Slot name="modal" errorFallback={ModalError} />Tests warn about React act
If you call router navigation methods directly in a test, wrap the call with React Testing Library or React act helpers when it causes a provider state update.
For click-driven navigation, prefer fireEvent.click() or userEvent.click() and then waitFor() assertions.
A hook says it requires a provider
The component is outside RouterProvider/StaticRouterProvider, or a duplicate React/router-react installation created a second context identity. Confirm one dependency instance before inventing a wrapper.