Astro Info

Astro                    v5.14.1
Vite                     v6.3.6
Node                     v22.19.0
System                   Windows (x64)
Package Manager          pnpm
Output                   static
Adapter                  none
Integrations             @astrojs/svelte (v7.2.0)

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

No response

Describe the Bug

This was brought up on discord earlier today. Svelte has had a recent experimental async feature added recently. Astro is now giving a warning, even on a brand new project without any asynchronous code being used.

[svelte] experimental_async_ssr
Attempted to use asynchronous rendering without `experimental.async` enabled
https://svelte.dev/e/experimental_async_ssr

Folks on discord said the issue might be upstream.

What's the expected result?

The above is from a simple 5-line .svelte component that is supposed to show a number. The component works just fine, but the warning is still there in the terminal. Functionally, there doesn't seem to be any issue, at least when you're not actually using the async ssr feature.

Link to Minimal Reproducible Example

https://stackblitz.com/edit/github-tpnsqnas?file=src%2Fpages%2Findex.astro

Participation

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