ENOENT error whenever I change a route module's exports

[rossipedia]

I'm using React Router as a...

framework, SSR-enabled

Reproduction

Unfortunately I have not been able to create a minimal reproduction. The only place I see this is in our (Docker) internal web monorepro. I'd be more than happy to get on a Zoom call or similar with somebody to demonstrate the issue.

System Info

System:
    OS: macOS 15.4.1
    CPU: (12) arm64 Apple M2 Max
    Memory: 4.35 GB / 64.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.15.0 - ~/.local/state/fnm_multishells/61607_1747190035669/bin/node
    npm: 11.3.0 - ~/.local/state/fnm_multishells/61607_1747190035669/bin/npm
    pnpm: 10.7.1 - ~/.local/state/fnm_multishells/61607_1747190035669/bin/pnpm
    bun: 1.2.5 - ~/.bun/bin/bun
  Browsers:
    Brave Browser: 111.1.49.132
    Chrome: 136.0.7103.93
    Edge: 136.0.3240.64
    Safari: 18.4

Used Package Manager

yarn

Expected Behavior

I should be able to change a route module's exports (default, loader, action, clientAction, `clientLoader, etc…) and HMR should work and I should be able to reload the page in my browser without error.

Actual Behavior

When I add/remove one of the React Router route module exports, my dev server reloads, but I see this error in terminal output, and my express error handler is always triggered (this is the error handler that is added after the React Router handler, and is used as a "catch-all" final error handler when things go catastrophically wrong).

11:13:16 AM [vite] Pre-transform error: ENOENT: no such file or directory, open './build/client/.vite/manifest.json'
11:13:16 AM [vite] Error when evaluating SSR module virtual:react-router/server-build:
|- Error: ENOENT: no such file or directory, open './build/client/.vite/manifest.json'

This error gets "stuck" and I have to kill the process with SIGINT (Ctrl-C) and restart the process to get things working again.

[timdorr]

What does your vite.config.ts or react-router.config.ts (if you have one) look like?

Based on what you've said, you've got a custom Express server instead of using the @react-router/dev server. Does your setup look significantly different from this?

const viteDevServer =
  process.env.NODE_ENV === 'production'
    ? undefined
    : await import('vite').then(vite =>
        vite.createServer({
          server: { middlewareMode: true, hmr: { server }, allowedHosts: true },
          appType: 'custom'
        })
      )

const reactRouterHandler = createRequestHandler({
  build: viteDevServer
    ? () => viteDevServer.ssrLoadModule('virtual:react-router/server-build')
    : await import('./build/server/index.js')
})

[rossipedia]

Yeah that's basically what we have, although we do some things to wrap the loaded route modules (instrumentation and such) before handing the ServerBuild off to createRequestHandler()

I can try removing those enhancers and seeing if I can still reproduce the issue.

react-router.config.ts is effectively this:

export default {
  serverModuleFormat: 'esm',
  future: {
    unstable_middleware: true,
    unstable_optimizeDeps: true,
  },
  ssr: true,
};

vite.config.ts is a bit complicated, but the plugins part looks like this:

    plugins: [
      envOnlyMacros(),
      viteCommonjs(),
      mdx({ remarkPlugins: [remarkFrontmatter, remarkMdxFrontmatter] }),
      tsconfigPaths({ loose: true }),
      ...(process.env['NODE_ENV'] !== 'test'
        ? [reactRouter(), safeRoutes({ outDir: 'types' })]
        : []),
      cjsInterop({
        dependencies: [
          '@mui/system/**',
          'attr-accept',
          'uuid',
          // Prod build only
          ...(process.env['NODE_ENV'] === 'production'
            ? ['safe-stringify', 'indent-string']
            : []),
        ],
      }),
    ],

I might be able to trim that down, but we're still on MUI 6, which has rather severely broken packaging, which is why we need the viteCommonjs() and cjsInterop() plugins.

We've had to apply the workaround that @markdalgleish wrote about here as well.

[rossipedia]

Note: I've had conversations on Discord with @brophdawg11 and @pcattori about this, it was requested that I make a GH issue so that it doesn't slip through the cracks.