Path syntax warnings appear in production

[floatingdino]

Reproduction

1. Go to https://stackblitz.com/edit/vitejs-vite-bcm7fxcs?file=src%2FApp.tsx
2. Observe console warnings

System Info

System:
    OS: macOS 15.5
    CPU: (16) arm64 Apple M4 Max
    Memory: 12.01 GB / 128.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.19.0 - ~/.nvm/versions/node/v20.19.0/bin/node
    npm: 10.8.2 - ~/.nvm/versions/node/v20.19.0/bin/npm
    pnpm: 10.8.0 - ~/Library/pnpm/pnpm
  Browsers:
    Chrome: 138.0.7204.101
    Safari: 18.5
  npmPackages:
    react-router: ^7.6.3 => 7.6.3 
    vite: ^6.0.1 => 6.3.5

Used Package Manager

npm

Expected Behavior

Developer warnings are hidden in production builds

Actual Behavior

Developer warnings are thrown to console in production

[timdorr]

I'm not seeing any console warnings in that reproduction. Can you try just a plain GitHub repo for us to look at?

[floatingdino]

Here's a github repo: https://github.com/floatingdino/react-router-warning-bug

For reference the warning I see in this repro is Route path "x*" will be treated as if it were "x/*" because the *character must always follow a/ in the pattern. To get rid of this warning, please change the route path to "x/*".

The warning is fine, but it continues to appear in a production build. Other warnings are correctly hidden in production.

[timdorr]

After looking at this a little more deeply, this is intentional behavior. Anything that uses our warning helper doesn't strip out those messages from production builds (with a few exceptions for future flags) and will remain. This is helpful for debugging in production scenarios as well, as it might point you to the underlying issue faster than simply receiving a seemingly unrelated error or, worse, no error at all.

[floatingdino]

I understand your angle, but I also ran into this warning Matched leaf route at location ... which seems to be hidden in production (see

react-router/packages/react-router/lib/hooks.tsx

Lines 536 to 551 in 11e1db8

	if (ENABLE_DEV_WARNINGS) {
	warning(
	parentRoute || matches != null,
	`No routes matched location "${location.pathname}${location.search}${location.hash}" `
	);
	warning(
	matches == null ||
	matches[matches.length - 1].route.element !== undefined ||
	matches[matches.length - 1].route.Component !== undefined ||
	matches[matches.length - 1].route.lazy !== undefined,
	`Matched leaf route at location "${location.pathname}${location.search}${location.hash}" ` +
	`does not have an element or Component. This means it will render an <Outlet /> with a ` +
	`null value by default resulting in an "empty" page.`
	);
	}

), and other warnings like You rendered descendant Routes... (

react-router/packages/react-router/lib/hooks.tsx

Lines 455 to 488 in 11e1db8

	if (ENABLE_DEV_WARNINGS) {
	// You won't get a warning about 2 different <Routes> under a <Route>
	// without a trailing *, but this is a best-effort warning anyway since we
	// cannot even give the warning unless they land at the parent route.
	//
	// Example:
	//
	// <Routes>
	// {/* This route path MUST end with /* because otherwise
	// it will never match /blog/post/123 */}
	// <Route path="blog" element={<Blog />} />
	// <Route path="blog/feed" element={<BlogFeed />} />
	// </Routes>
	//
	// function Blog() {
	// return (
	// <Routes>
	// <Route path="post/:id" element={<Post />} />
	// </Routes>
	// );
	// }
	let parentPath = (parentRoute && parentRoute.path) || "";
	warningOnce(
	parentPathname,
	!parentRoute || parentPath.endsWith("*") || parentPath.endsWith("*?"),
	`You rendered descendant <Routes> (or called \`useRoutes()\`) at ` +
	`"${parentPathname}" (under <Route path="${parentPath}">) but the ` +
	`parent route path has no trailing "*". This means if you navigate ` +
	`deeper, the parent won't match anymore and therefore the child ` +
	`routes will never render.\n\n` +
	`Please change the parent <Route path="${parentPath}"> to <Route ` +
	`path="${parentPath === "/" ? "*" : `${parentPath}/*`}">.`
	);
	}

) also have code to check whether the build is in production. I would love to understand why some warnings have this check and others seem to omit it?