Works in CF Workers, doesn't in Miniflare

[PH4NTOMiki]

I'v been trying to use Remix(https://remix.run), and it uses Miniflare for dev server(if CF Workers chosen as output platform) and I have a code that works when deployed to CF Workers, , this is the code for the route:

export let action = async ({ request }) => {
  let formData = await request.formData();
  let answer = formData.get("answer");

  // Typical action workflows start with validating the form data that just came
  // over the network. Clientside validation is fine, but you definitely need it
  // server side.  If there's a problem, return the the data and the component
  // can render it.
  if (typeof answer !== "string") {
    return json("Come on, at least try!", { status: 400 });
  }

  if (answer !== "egg") {
    return json(`Sorry, ${answer} is not right.`, { status: 400 });
  }

  // Finally, if the data is valid, you'll typically write to a database or send or
  // email or log the user in, etc. It's recommended to redirect after a
  // successful action, even if it's to the same place so that non-JavaScript workflows
  // from the browser doesn't repost the data if the user clicks back.
  return redirect("/demos/correct");
};

but in dev server I get this in terminal

[mf:err] POST /demos/actions?_data=routes%2Fdemos%2Factions: TypeError: Response with null body status cannot have body
    at new Response (/home/mutic/dev/my-remix-app/node_modules/undici/lib/fetch/response.js:160:15)
    at new Response (file:///home/mutic/dev/my-remix-app/node_modules/@miniflare/core/src/standards/http.ts:393:13)
    at Object.construct (file:///home/mutic/dev/my-remix-app/node_modules/@miniflare/core/src/plugins/core.ts:62:29)
    at handleDataRequest (/home/mutic/dev/my-remix-app/node_modules/@remix-run/server-runtime/server.js:170:12)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at /home/mutic/dev/my-remix-app/node_modules/@remix-run/server-runtime/server.js:66:20
    at handleEvent (/home/mutic/dev/my-remix-app/node_modules/@remix-run/cloudflare-workers/worker.js:93:18)
    at EventTarget.[kDispatchFetch] (file:///home/mutic/dev/my-remix-app/node_modules/@miniflare/core/src/standards/event.ts:356:13)
    at Server.<anonymous> (file:///home/mutic/dev/my-remix-app/node_modules/@miniflare/http-server/src/index.ts:165:20)
POST /demos/actions?_data=routes%2Fdemos%2Factions 500 Internal Server Error (145.70ms)

[RossJHagan]

Some context as I ran into this issue and did some digging.

The creation of the Response in remix's server-runtime is using an empty string instead of null in a response with status code 204. As the behaviour in undici is to require a null body on a 204, it blows up.

Changing the server-runtime behaviour to create a response with null instead of "" in node_modules/@remix-run/server-runtime/server.js on line 170 corrects the behaviour. So looks like it may not be a miniflare issue.

Edit: see also: remix-run/remix#553

[rjgux]

Having a similar issue. Noticed a PR is open here remix-run/remix#547

[PH4NTOMiki]

Yeah, thanks @RossJHagan you're right, but still it works in CF Workers, so it should in the dev environment as well, since the Cloudflare policy is that they will never break a code that works in production, source: https://blog.cloudflare.com/backwards-compatibility-in-cloudflare-workers/ so it should work in Miniflare as well, and it should get fixed in Remix as well.

[mrbbot]

Hey! 👋 miniflare@2.0.0-rc.3 has just been released, including the fix for this. You can find the changelog here.