404 Response -> 404 page doesn’t work in dev server

[arty-name]

What version of astro are you using?

2.5.4

Are you using an SSR adapter? If so, which one?

no

What package manager are you using?

yarn

What operating system are you using?

Linux

What browser are you using?

Firefox

Describe the Bug

The newly added feature Render 404 page content for existing pages with 404 Response does not seem to work in dev mode, and only works in the built application.

You can see in the Stackblitz that the index page renders nothing when astro dev is running. If you stop it and run astro build && astro preview, only then the 404 page will be rendered for the index page returning status 404.

Link to Minimal Reproducible Example

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

Participation

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

[paulrudy]

Just to add: Extra weirdness: after deploying (in my case to Vercel), navigating to a non-existent page /foo downloads a file named foo (Safari on Mac), rather than rendering a 404 page.

[predaytor]

experienced this too

[natemoo-re]

This was fixed in #7693 and should be released soon.

[jdbruxelles]

I use astro v2.10.4 and Netlify and my 404 page is served as a plain text in dev when I use ntl dev which runs astro dev. But, when I run ntl dev --live, my 404 page is rendered correctly.