Astro Info

Astro                    v5.16.6
Vite                     v6.4.1
Node                     v24.12.0
System                   macOS (arm64)
Package Manager          pnpm
Output                   static
Adapter                  none
Integrations             @astrojs/solid-js (v5.1.3)
                         @astrojs/sitemap (v3.6.0)

If this issue only occurs in one browser, which browser is a problem?

No response

Describe the Bug

When trailingSlash is set to anything other than ignore, query params cause a 404 page in dev mode.

Reproduction steps:

1. Set the base path in the config
2. Set trailingSlash to never
3. Navigate to the index page (now at the base path) – works fine
4. Add query params to the URL and refresh – results in a 404 error

What's the expected result?

Page loads fine

Link to Minimal Reproducible Example

https://stackblitz.com/edit/withastro-astro-svbaysc1?file=astro.config.mjs

Participation

• I am willing to submit a pull request for this issue.