Description

After upgrading from Astro 6.1.2 to 6.1.3, Netlify deploys fail with a Vite/esbuild error. Builds succeed locally on Windows but fail on Linux (Netlify).

Error

[ERROR] [vite] ✗ Build failed in 90ms
Syntax error "c"
  Hint: Browser APIs are not available on the server.
  Location: _astro/ContactForm.astro_astro_type_script_index_0_lang.!~{004}~.js:105:153

Root cause

Vite/Rollup uses !~{NNN}~ as internal placeholders for chunk content hashes during the build. In a final pass, these are replaced with actual hashes (e.g. DJeACKAp).

• On Windows (local builds): placeholders resolve correctly. Output file is named ContactForm.astro_astro_type_script_index_0_lang.DJeACKAp.js.
• On Linux (Netlify): placeholders are not resolved. The file retains !~{004}~ in its name.
• The @astrojs/netlify adapter then runs esbuild to bundle the SSR function. esbuild encounters the ! and ~ characters in the filename and fails with Syntax error "c".
• The "Browser APIs are not available on the server" hint is misleading — the actual failure is esbuild choking on special characters in the chunk filename.
• Affects any inline <script> in Astro components, not just ones with dynamic imports.

Bisection

The regression was introduced in 6.1.3. All tests used @astrojs/netlify@7.0.6.

6.1.3 patches analysis

I initially suspected #16110 (pluginChunkImports), but after reading the source, the plugin returns undefined when assetQueryParams is not set and is filtered out by .filter(Boolean) — it's a no-op for non-Vercel adapters.

The remaining candidates from the 6.1.3 changelog:

• fix: stop CSS traversal at page boundaries #16116 — CSS leak fix (touches build output traversal)
• fix(astro): Fix isHTMLString check failing in multi-realm environments #16142 — MDX/AstroContainer HTML escaping
• Include injected routes when checking if renderers are needed in SSR builds #16178 — SSR builds with injected routes

Reproduction

1. Create an Astro project with @astrojs/netlify adapter
2. Add a component with an inline <script> tag (e.g. <script>import('canvas-confetti')</script>)
3. Deploy to Netlify with astro@6.1.3
4. Build fails with the error above

Downgrading to astro@6.1.2 resolves the issue.

Environment

• Astro: 6.1.3 (fails), 6.1.2 (works)
• @astrojs/netlify: 7.0.6
• Node: 22.x (tested with both 22.18.0 and 22.22.2 — same result)
• Local OS: Windows 10 (builds succeed)
• Deploy OS: Linux (Netlify, builds fail)

Same bug reproduces across two separate sites with the same stack.