Server-rendered 404 pages no longer work on Cloudflare

[ToxiWoxi]

What version of astro are you using?

2.9.7 to 3.3.2

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

Cloudflare

What package manager are you using?

npm

What operating system are you using?

Linux & Deployment

What browser are you using?

Chrome

Describe the Bug

Issue: Changes to 404 handling have resulted in server-rendered 404 pages no longer working on Cloudflare.

Behaviors in different versions

Expected behavior:

1. The 404 page loads when going to a non-existent route
2. The 404 page can perform redirects to case-corrected versions of pages or aliases will redirect to correct page
   • Examples:
     • /eXaMPLe can be redirected to /example
     • /index can be redirected to /

• These behaviours are tested to work in Astro v2.9.6 with Cloudflare adapter v6.6.2

Updated behavior with Astro v2.9.7 and higher

1. Cloudflare sends a default 404 error with no page when accessing a non-existent route
2. The 404 page still can be accessed from /404
3. Case-corrections and aliases will not be redirected

• These behaviours are tested to work in Astro v2.9.7 and higher with Cloudflare adapter v6.6.2

Updated behavior with Cloudflare adapter v6.7.0 and higher

1. Cloudflare returns with the contents of the index route without redirecting or updating the url when accessing a non-existent route
2. The 404 page still can be accessed from /404
3. Case-corrections and aliases still will not be redirected

• These behaviours are tested to work in Astro v2.10.5 and higher with Cloudflare adapter v6.7.0 and higher and is the current behavior on latest versions of both.

This issue does not happen on latest when prerendering the 404 page

However, this doesn't allow you to use the 404 page to do case-corrections and handle aliases

• The latest-prerendered deployment in my provided example dedicated to this behavior

Deployments and their issues

Deployment	Bad Routes	Aliases	Case-correction
astro@2.9.6	Returns 404.astro	Working	Working
astro@2.9.7	Returns nothing	Configured redirects only	Not working
astro@2.10.5-cloudflare@6.6.2	Returns nothing	Configured redirects only	Not working
astro@2.10.5-cloudflare@6.7.0	Returns index.astro	Configured redirects only	Not working
latest	Returns index.astro	Configured redirects only	Not working
latest-prerendered	Renders 404.astro	Configured redirects only	Not working

What's the expected result?

1. The 404 page loads when going to a non-existent route
2. The 404 page can perform redirects to case-corrected versions of pages or aliases will redirect to correct page
   • Examples:
     • /eXaMPLe can be redirected to /example
     • /index can be redirected to /

• These behaviours are tested to work in Astro v2.9.6 with Cloudflare adapter v6.6.2

Link to Minimal Reproducible Example

https://github.com/ToxiWoxi/astro-404-issue

Participation

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

[natemoo-re]

Thanks for the thorough details and sorry for the frustration! We're tracking down quite a few 404 related issues (withastro/astro#8070) and hoping to fix them soon. The original changes probably shouldn't have gone out in a patch release.

[xriter]

This might be the same / related to issue withastro/astro#8054

[lilnasy]

The issues described here are trickier, unfortunately.

[smastrom]

I'm having the same issue, I'll add more context maybe it can help. In my case, I'm using output: server to deploy a bilingual website to Cloudflare Pages. I have a 404.astro and index.astro which share the same logic:

---
const lang = Astro.request.headers.get('Accept-Language')

if (lang.startsWith('it')) return Astro.redirect('/it')

return Astro.redirect('/en')
---

On local dev, both work as expected. Once deployed, If try to access a non-existent page the cloudflare server returns a 500 errror. The index page logic works as expected instead.

[alexanderniebuhr]

Can we confirm that this is still an issue. I do have projects deployed with 404.astro pages, and it works.

[alexanderniebuhr]

Closing for now, because the Issue seems to be stale. Happy to reopen, if we get new information or confirmation.

[ToxiWoxi]

Sorry, the last replies were sent to my spam.
This is still an issue. I've updated the "latest" branch in my repo to use Astro 3.5.3 and Cloudflare adapter 7.7.0 (latest versions at current time), which you can preview here and look at the code here.
Once again, this is the expected behavior, last working with Astro 2.9.6 and Cloudflare adapter version 6.6.2.

[lilnasy]

Thanks for your effort, ToxiWoxi!
I'll try to take a look this week.

[alexanderniebuhr]

Ok just to clear some things about this issue. We need to different where the fallback routing for a 404 page happens.

• Cloudflare Pages does only fallback to a 404.html file. That is the reason why it does work for a pre-rendered 404 page, the dist folder will have a 404.html file, therefore Cloudflare does handle the fallback routing for any route which is not found.
• If the 404 page should be rendered using SSR, it would be up to Astro or the adapter to make sure the fallback works, because Cloudflare would not handle fallback routing in that case.
• We need to find out if a change in Astro causes the redirect to a 404 if the page does not exist do not trigger, or if the adapter code changed. (I currently expect it to be a Astro issue, not an adapter one. But I'll quickly check the Adapter changes)

[alexanderniebuhr]

@lilnasy this was the PR which moved the logic from the adapter to Astro. Not sure if that matches the time range, aligning with the versions in this report. https://github.com/withastro/astro/pull/4018/files