[WARN] Astro.request.headers is not available in "static" output mode.

[mrcnski]

Astro Info

Astro                    v4.4.3
Node                     v21.5.0
System                   macOS (arm64)
Package Manager          npm
Output                   static
Adapter                  none
Integrations             none

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

No response

Describe the Bug

Since upgrading to Astro 4.4.3 I'm getting this warning in the console:

[WARN] `Astro.request.headers` is not available in "static" output mode. To enable header access: set `output: "server"` or `output: "hybrid"` in your config file.

What's the expected result?

I was not getting this warning on Astro 4.3.7.

I'm not doing anything with headers AFAIK, but it would be nice to have a trace to know where this warning is coming from.

I tried for some time but I'm having trouble reproducing this on Stackblitz or in a fresh project. As mentioned above, a trace would be nice. My project is simple, my only dependencies are Astro and Typescript.

Link to Minimal Reproducible Example

https://stackblitz.com/see-above

Participation

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

[Reyno-Skeps]

Can confirm, running into the same issue right now.

[Princesseuh]

Will be fixed by #10196, sorry for the inconvenience. It's a bug with i18n in particular

[mrcnski]

Awesome! Sorry, I searched existing issues but didn't think to search PRs.

[bluwy]

#10196 has been merged

[mrcnski]

I've confirmed that this has been fixed as of 4.4.5, thanks everybody.

[eitelkrauss]

I just upgraded to 4.5.9 and I'm running into this issue. The warning is only for my prerendered pages. I have output: 'server'

[boredland]

can confirm this still is a problem with hybrid, i18n and such a .astro file:

---
import { getHeadersLocale } from '../utils/headersLocale'

const locale = getHeadersLocale(Astro.request.headers.get('accept-language') ?? 'en')
  
return Astro.redirect(`/${locale}`)
---

[matthewp]

This is intentional. You can't read headers in a static page. We do this on purpose so that you don't rely on behavior that will lead to build-time and run-time differences.

[eitelkrauss]

@matthewp I'm not reading any headers though.

EDIT: I was reading headers.. sorry

[daolanfler]

---
import ThemeToggle from "./ThemeToggle";
const cookie = Astro.cookies.get("theme");

export const prerender = false;
---

<ThemeToggle themeCookie={cookie?.value} client:load />

I have a ThemeToggle component like this, this component is accessing cookie in headers. And my astro.config.mjs is output: hybrid. This component runs on server instead of client as I've specified prerender=false, but I still get the warning, and I thinks it's ok to access headers in this situation...

[rottmann]

Hint: this error occurs on symbolic linked files too, even if prerender is set to false.

[xabru]

I encountered the same warning again in the latest update "4.16.1." I had to downgrade to "4.16.0" to make the warning disappear in a project created from scratch using bun create astro.

[jahands]

Same here, running Astro on Cloudflare Workers. Just upgraded and started getting this warning. I also have an endpoint that started failing with this error on the server side:

(error) 12:28:48 [ERROR] TypeError: Can't modify immutable headers.
    at setOriginHeader (_worker.js:163:25960)
    at RenderContext.create (_worker.js:165:3228)
    at async bn.render (_worker.js:180:186)
    at async Object.fetch (_worker.js:180:5208)

(not sure if related or if this is a separate issue.)
edit: separate issue: #12201

[yoyo837]

Same warning in 4.16.14

[Mistwell]

Same warning in "astro": "^4.16.13",
just have 2 static mainpages with i18n

[ematipico]

@Mistwell update to the latest, this was fixed

[yoyo837]

4.16.15 fixed this.

[vv3rd]

Encountered this issue on 4.16.15 when Astro.rewrite is used.
To reproduce create src/pages/[your_locale_of_choice]/test.astro with

---
return Astro.rewrite('/anohter-page')
---

Warning goes away if you pass new instance of Request

---
return Astro.rewrite(new Request(new URL('/another-page', Astro.url.origin)));
---