ErrorBoundary with an `Outlet` component re-render the current route before the next route

Which project does this relate to?

Router

Describe the bug

Situation

I use a pathless route and the layout is used in order to have a generic ErrorBoundary to catch any error, display the error and show a retry button.

If an error occurs and we try to navigate to another route, the erroneous component (of the current route) will re-render before the new route. This can cause some re-fetch to occurs if the component error was due to some fetching error (which is usually the case). This slow down the application and can lead to some unexpected side-effect.

Your Example Website or App

https://stackblitz.com/edit/github-dgnsgk?file=src%2Froutes%2F_app.tsx

Steps to Reproduce the Bug or Issue

1. Open the console
2. Go to the Posts route. An error will be displayed.
3. Navigate to any other route.

Expected behavior

The Posts component should not be re-render before rendering the new route.

Screenshots or Videos

https://github.com/user-attachments/assets/c3676941-0eb4-4f45-a958-1c704032428b

Platform

• OS: macOS (only tried on macOS but it is surely the same on Windows)
• Browser: Brave, Chrome, Safari, Firefox
• Version: 1.57.9

Additional context

ErrorBoundary and resetKey

From what I see, the resetKey of the ErrorBoundary which is set to [location.pathname] from Tanstack Router useLocation resets before the <Outlet /> render the new route.

So the sequence can look like :

1. Click on Link component to navigate to a new route
2. location.pathname change, thus it will reset the ErrorBoundary and the current component displayed in Outlet component
3. Outlet component render the new route

I'm not really sure if this is an issue on Tanstack Router or if this is a general issue on how ErrorBoundary component works. But I feel like the location should be in sync with the Outlet Component in the render cycle.

React Router

I first thought it was a react query issue, I have searched in every repo (react-query and react-router) to find about the issue but could only find something related to the Errored queries caught by ErrorBoundary are not retried on mount (https://github.com/TanStack/query/issues/271) and first posted a comment there https://github.com/TanStack/query/issues/2712#issuecomment-2335173812.

Solution

The current solution is to wrap every route inside a custom ErrorBoundary component but this remove the utility of a pathless route and the use of a layout which was a good fit for this use case.
My example use a pathless route with a layout component but the issue could surely be reproduced with a normal route that wrap the Outlet component inside an ErrorBoundary

Start with the linked StackBlitz reproduction, especially src/routes/_app.tsx, and inspect the ErrorBoundary, Outlet, Link, and useLocation interactions described in the report. Reproduce the Posts-route error, navigate to another route, and compare the render sequence with the expected behavior: the errored Posts component should not render before the new route.