# Astro astro@6.4.7 — Release & Upgrade Intelligence
- **Product:** Astro (https://astro.build)
- **Version:** astro@6.4.7
- **Released:** Jun 15, 2026
- **Impact Score:** 7/10
- **Breaking Changes:** Source flagged
- **Canonical Analysis:** https://changelogs.us/astro/updates/astro-6.4.7/

## Executive Summary (TL;DR)
Astro astro@6.4.7. Source highlight: Fixes `getRelativeLocaleUrl`, `getAbsoluteLocaleUrl`, and `getAbsoluteLocaleUrlList` to strip trailing slashes when `trailingSlash: 'never'` is configured

## Breaking Changes & Deprecations
- When custom elements (tags with hyphens like `<my-element>`) are used in MDX files, the `slot` HTML attribute on their children is now correctly preserved. Previously, the shared JSX runtime would treat `slot` as an Astro slot assignment and remove it from the output, breaking Shadow DOM named slot distribution for web components.

## Bug Fixes
- Fixes `getRelativeLocaleUrl`, `getAbsoluteLocaleUrl`, and `getAbsoluteLocaleUrlList` to strip trailing slashes when `trailingSlash: 'never'` is configured
- Fixes double URL-encoded paths returning 400 Bad Request on on-demand routes
- Fixes prerendered redirect targets being incorrectly bundled into the SSR function in hybrid mode, causing massive bundle size inflation
- fix(render): honour compressHTML when joining head elements
- Fixes custom elements in MDX having their children's `slot` attribute stripped by the JSX runtime
- Fixes stale inline CSS in server-rendered HTML after CSS file edits during dev

## Upgrade Command
```bash
npm install --save-exact astro@6.4.7
```