Custom 404 page not working on Vercel (output mode static)

[devmatteini]

Astro Info

Astro                    v4.0.9
Node                     v18.18.2
System                   Linux (x64)
Package Manager          npm
Output                   static
Adapter                  @astrojs/vercel
Integrations             @astrojs/tailwind
                         astro-icon
                         @astrojs/mdx

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

No response

Describe the Bug

• Create a custom 404.astro page.
• Deploy to Vercel with Astro output mode on static
  I use vercel cli:

  vercel pull --yes --environment production --token "$VERCEL_TOKEN"
  astro build
  vercel deploy --prebuilt --prod --token "$VERCEL_TOKEN"
  

• Open your website in a non-existing route and the custom 404 page is not shown. The vercel 404 default page is shown instead.
  

This is the repository: https://github.com/devmatteini/website
I just ported this repository from Next.js to Astro, so I might have done something wrong somewhere.

Just to give more information, I can see from Vercel deployment Source tab that the deployed files and the 404.html exists (.vercel/output/static/404.html).

This is the rest of the content:

Interestingly, if you go to https://<domain>/404.html the custom 404 page is rendered correctly.

What's the expected result?

The custom defined 404 page should be used instead of Vercel's default one when reaching a non-existing route

Link to Minimal Reproducible Example

I'm not sure a minimal example with Vercel is doable since it would require a personal Vercel account

Participation

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

[florian-lefebvre]

Instead of a repro, you could create a minimal github repo (I didn't have a look but looks like it's already the case) and host the website on vercel until this issue is closed

[devmatteini]

Hi! If you consider this repository minimal, it's already hosted on vercel (https://cosimomatteini.com/).

Otherwise, I can create a new repository with minimal setup.

[florian-lefebvre]

Not really minimal imo. Have a look at #9206 to see an example

[github-actions]

Hello @devmatteini. Please provide a minimal reproduction using a GitHub repository or StackBlitz. Issues marked with needs repro will be closed if they have no activity within 3 days.

[lilnasy]

Can you try @astrojs/vercel@experimental--9591?

[devmatteini]

Here it is a minimal repo to reproduce the issue: https://github.com/devmatteini/astro-vercel-404-issue
Website: https://astro-vercel-404-issue.vercel.app/

[devmatteini]

Can you try @astrojs/vercel@experimental--9591?

I installed it, but it didn't solve the issue

[devmatteini]

@lilnasy Starting from your patch, I changed the src value to /.* and now it works!

[lilnasy]

Forgot I was doing regex 😭

Thanks for looking into it!

[devmatteini]

Thank you @lilnasy for your work!