vite 5 preview return 404 on / if Accept Header is missing

[StefanSchoof]

Describe the bug

1. Start vite preview
2. Request / with Accept Header gives a 200 and the index.html
   
3. Request / without Accept Header gives a 404 and a empty body
   

This is a changed behavior to vite 4.

This lead to that npx wait-on http://localhost:4173 will never finish and blocks. Which is also used in https://github.com/cypress-io/github-action#wait-on. The workaround is to use npx wait-on http://localhost:4173/index.html

If I read the rfc right this behavior is also not according to https://www.rfc-editor.org/rfc/rfc7231#section-5.3.2

A request without any Accept header field implies that the user agent
will accept any media type in response.

The minimal reproduction is only a new project with npm create vite@latest

Reproduction

https://github.com/StefanSchoof/vite-empty-accept

Steps to reproduce

1. npm run build
2. npm run preview

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
    Memory: 6.43 GB / 31.73 GB
  Binaries:
    Node: 20.9.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.1.0 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Spartan (44.19041.3636.0), Chromium (119.0.2151.58)
    Internet Explorer: 11.0.19041.3636
  npmPackages:
    vite: ^5.0.0 => 5.0.0

Used Package Manager

npm

Logs

No response

Validations

• Follow our Code of Conduct
• 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.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[StefanSchoof]

Thanks @sapphi-red , that was quick.

[titenis]

Is this really fixed? Still getting errors:

yarn vite preview & yarn wait-on http://localhost:4173 --verbose
[1] 3940
  ➜  Local:   http://localhost:4173/
  ➜  Network: use --host to expose
  ➜  press h + enter to show help
waiting for 1 resources: http://localhost:4173
making HTTP(S) head request to  url:http://localhost:4173 ...
  HTTP(S) error for http://localhost:4173 AxiosError: Request failed with status code 404

[patak-dev]

@titenis the fix was released a few hours ago in v5.0.1, please check that you have that version. If it is still failing, please create a new issue with a minimal repro (maybe you hit another issue)

[sapphi-red]

I reproduced it. I should have tested with wait-on as well.