instanceof RunnableDevEnvironment fails with vite-plus alias #7218

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1. schiller-manuel commented on Apr 18, 2026

   

   schiller-manuel

   on Apr 18, 2026

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   please provide a reproducer that can be cloned directly without having to execute any more installation. also try different package managers to find out if it depends on that
2. TanStack

   deleted a comment from davyleotte-eng on Apr 18, 2026
3. TanStack

   deleted a comment from davyleotte-eng on Apr 18, 2026
4. schiller-manuel

   added

   information neededFurther information is requestedFurther information is requested

   on Apr 18, 2026
5. ultra2207 commented on Apr 18, 2026

   

   ultra2207

   on Apr 18, 2026

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   you can clone what i linked above directly, but yeah it is an issue with vite+ specifically. Using npm or bun to start thr vite server does fine. However since the fix for the issue is in tanstack router code and not in vite-plus code i opened the issue here.

   Reproduction simply involves git cloning the above, installing vite-plus, cd into it and then do vp run.
6. schiller-manuel commented on Apr 18, 2026

   

   schiller-manuel

   on Apr 18, 2026

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   why dont you install vite-plus then in the repo? it might matter which package manager you use for that step.
7. ultra2207 commented on Apr 18, 2026

   

   ultra2207

   on Apr 18, 2026

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   the regular vp install using irm https://vite.plus/ps1 | iex installs globally, not in the repo. Also just putting it in the repo wont work as its different for windows/mac/linux. Not to mention adding to path which the command does automatically.
8. ultra2207 commented on Apr 19, 2026

   

   ultra2207

   on Apr 19, 2026

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   yo
9. roll commented on May 26, 2026

   

   roll

   on May 26, 2026

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   It seems to be we are running into the same, a mostly empty Tanstack Start app does work with vite dev and 404 on any route with vp dev (pnpm managed)
10. kevinkod commented on Jun 8, 2026

    

    kevinkod

    on Jun 8, 2026

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    Corroborating data point from a different setup (npm workspaces, not the OP's global vite-plus install), in case it helps move this out of "information needed".

    Environment

    • npm workspaces monorepo (not pnpm/bun), vite aliased to vite-plus via root overrides: "vite": "npm:@voidzero-dev/vite-plus-core@latest"
    • @tanstack/react-start SSR app, vp dev
    • Reproduces identically against [email protected], 1.168.14, and with [email protected]; also against [email protected]/0.1.21/0.1.22 and plain npx vite (vite 8.0.14). The @tanstack/* version is not the variable — the vite-plus alias is.

    Symptom: vp dev boots fine but every route returns 404 Cannot GET /. vite dev (real vite) works.

    Where it bails — start-plugin-core/dist/esm/vite/dev-server-plugin/plugin.js:

    if (installMiddleware == void 0) {
      if (viteDevServer.config.server.middlewareMode) return;
      if (!isRunnableDevEnvironment(serverEnv) || "dispatchFetch" in serverEnv) return; // ← silent bail, no log
    }

    Under the vite-plus alias the SSR environment isn't recognized as a RunnableDevEnvironment, so the dev middleware is never installed and every request 404s. Note the bail is silent — there's no warning, which is what makes this hard to diagnose. The throw a few lines down (cannot install vite dev server middleware ... not a RunnableDevEnvironment) is never reached because of the early return.

    Workaround that works for us — a pre plugin that forces the SSR env to be Runnable, using createRunnableDevEnvironment resolved through the same (aliased) vite specifier:

    import { createRunnableDevEnvironment } from "vite";
    import type { Plugin } from "vite";
    
    function forceRunnableSsrEnvironment(): Plugin {
      return {
        name: "force-runnable-ssr-env",
        enforce: "pre",
        config() {
          return {
            environments: {
              ssr: { dev: { createEnvironment: (name, config) => createRunnableDevEnvironment(name, config) } },
            },
          };
        },
      };
    }

    With this, the middleware installs and SSR HTML is served (HTTP 200) under vp dev.

    Two possible upstream fixes, fwiw:

    1. Have start-plugin-core set environments.ssr.dev.createEnvironment = createRunnableDevEnvironment itself when configuring the SSR env (it currently sets consumer: 'server' but doesn't pin the dev environment factory), so it doesn't depend on the host's default being Runnable.
    2. Expose installDevServerMiddleware to the vite plugin config (today only the rsbuild path reads it per schema.js), so users can opt in without patching the package.

    Happy to provide a minimal npm-workspaces reproducer if useful.
11. qeeqez commented on Jul 11, 2026

    

    qeeqez

    on Jul 11, 2026

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    similar issue for the Vite 8 release - #7614
12. schiller-manuel commented on Sep 7, 2026

    

    schiller-manuel

    on Sep 7, 2026

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    fixed upstream voidzero-dev/vite-plus#1391
13. schiller-manuel

    closed this as completedon Sep 7, 2026