Rewrite returning a 500 in production but a 200 on localhost with netlify dev

I have this site: (code is on github).

The purpose of the site is to grab the HTML of any given URL and try to parse it for reading.

Because of CORS, I can’t do a client-side fetch to any URL on the web.

Instead, I leverage Netlify’s rewrites functionality to essentially fetch the HTML for any given URL and hand it back to me on the client-side.

To do this, my netlify.toml file has this rule in it:

  from = "/cors-proxy/*"
  to = ":splat"
  status = 200
  force = true

So, from my domain, if I do:


I’ll get a CORS issue. But if I hit my /cors-proxy path then pass the URL, Netlify’s redirects/rewrites engine will handle the fetching of that document for me without a CORS issue:


At least that’s the idea.

If I get my local server up and running with netlify dev and I hit localhost:8888/cors-proxy/URL, I see the response I would expect:

I even see that request show up in the log for netlify dev

But when I push my code and it deploys at my url, the exact same request returns a 500.

Trying a fetch request in the browser shows a 500 as well.

But this isn’t a problem on local development. I get a 200 locally. It only becomes a 500 when this goes live.

Why is that? What am I missing?

This might help:

1 Like

Ahhh well yes, that would explain it given that the blog post i wrote is specifically called out in that announcement as the kind of thing being deprecated. That explains why it used to work and all of the sudden is not working anymore.

Thx for the link