Vite uses and passes a different server instance to plugins after server restart

[Artur-]

Describe the bug

1. Start Vite using a basepath of /VAADIN
2. Request a non-existing file, e.g. curl http://127.0.0.1:5173/VAADIN/foo.js -v

Problem 1, index.html is returned:

< HTTP/1.1 200 OK
< Content-Type: text/html
< Content-Length: 1036

3. Request the file again, e.g. curl http://127.0.0.1:5173/VAADIN/foo.js -v

Now it works correctly:

< HTTP/1.1 404 Not Found
< Content-Length: 0

4. Restart Vite by pressing r+enter in the Vite console

5. Request the file again, e.g. curl http://127.0.0.1:5173/VAADIN/foo.js -v

Problem 1, index.html is returned again. And no matter how many times you request the file, index.html is returned.

The reason this is a problem is that we proxy requests to Vite and when Vite does not return a file, we check in other locations. Now when Vite returns the file that does not exist, we do not check for the real foo.js and instead serve the wrong file (index.html)

Reproduction

Presumably related to something in the project as it does not reproduce in a simple project

Steps to reproduce

No response

System Info

System:
    OS: macOS 14.2
    CPU: (10) arm64 Apple M1 Max
    Memory: 673.84 MB / 64.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.9.0 - ~/.nvm/versions/node/v20.9.0/bin/node
    npm: 10.1.0 - ~/.nvm/versions/node/v20.9.0/bin/npm
    bun: 1.0.7 - ~/.bun/bin/bun
  Browsers:
    Brave Browser: 107.1.45.123
    Chrome: 120.0.6099.216
    Chrome Canary: 122.0.6241.4
    Edge: 120.0.2210.133
    Safari: 17.2
    Safari Technology Preview: 17.4
  npmPackages:
    @vitejs/plugin-react: 4.2.0 => 4.2.0 
    @vitejs/plugin-react-swc: 3.5.0 => 3.5.0 
    vite: 5.0.11 => 5.0.11

Used Package Manager

npm

Logs

No response

Validations

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• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
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• The provided reproduction is a minimal reproducible example of the bug.

[Artur-]

Ok, this is probably a bug in our configuration as it only reproduces with that. Seems like it tries to remove viteHtmlFallbackMiddleware and fails to do that on restart

[Artur-]

The potential Vite issue here would be that server passed to

        transformIndexHtml: {
          order: 'pre',
          handler(_html, { server }) {

after a restart is not the same instance as the server used for determining which middlewares to use. Before a restart, they are the same

[Artur-]

The behavior has changed in 5.0.4

[Artur-]

So probably in #15166. Intentional @patak-dev? Should we fix our conf?

[patak-dev]

Yes, I think the fix you linked is correct here. 5.0.4 started to properly respect middlewares after a restart. Before, when using the documented way to setup the dev server for SSR: https://vitejs.dev/guide/ssr.html#setting-up-the-dev-server

  app.use(vite.middlewares)

you will always be using the middlewares created at server startup, and any changes after a restart were ignored.
Sorry for the glitch to your app in a patch. Let's close this issue.