Describe the bug

transformIndexHtml() prints the following error when HTML contains a relative link to a script, and url parameter ends in slash (i.e. /example/dir/, and not /example/dir/index.html):

Pre-transform error: Failed to load url /example/filename.js (resolved id: /example/filename.js). Does the file exist?

This can occur when implementing the dev server following the SSR guide.

Cause

This happens because dirname() of the html url is taken which, for a path that ends in slash, removes the directory name. And the file is searched in the parent directory:

When using builtin vite server, it converts urls that end in slash to absolute filesystem paths that end in index.html:

but this doesn't happen for the SSR example since:

1. It uses appType: 'custom', which disables this url preprocessing
2. The custom handler uses req.originalUrl, which is not modified
3. The HTML file may not exist

Reproduction

https://stackblitz.com/edit/vitest-dev-vitest-bx1fvf91?file=index.js

Steps to reproduce

1. npm install
2. npm run dev
3. Observe the error message in console:

Pre-transform error: Failed to load url /example/filename.js (resolved id: /example/filename.js). Does the file exist?

4. Ctrl+C
5. Change /example/dir/ on line 4 to example/dir/index.html
6. npm run dev
7. Observe no error

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (2) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    vite: latest => 5.4.11

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.

Workaround

1. Don't use originalUrl (it breaks if base is set to some directory). Use req.url`
2. Remove query parameters an hashes from the url, so that only the path is left
3. If it ends in /, add index.html to it
4. Pass this path to transformIndexHtml