SvelteKit (Vite) POST request resulting in "Function not found..." response message.

[kyllerss]

UPDATED: After the original issue disappeared with a netlify update, the issue recently reappeared. See the comments below for details. I have provided a minimal recreation in the comments.

Describe the bug

I am using SvelteKit in my project. My site seems to work well for all GET requests including those that leverage endpoints. However, I have one endpoint that has handlers for both GET and POST requests. The GET request works fine, however when I submit a POST request to that same endpoint, I get the text response message "Function not found...".

This is not a problem I run into when running SvelteKit directly instead of through netlify-cli.

I verified that the corresponding .netlify/server/entries/endpoints file has both GET and POST functions.

Any suggestions for things to try? If this is a head-scratcher, I'll move forward with creating a test project that reproduces the issue.

Steps to reproduce

Submit a POST request to an enpoint that defines both GET and POST handlers.

Configuration

[build]
command = "npm run build"
publish = "dist" 

[dev]
  command = "npm run dev -- --host" 
  targetPort = 5173 
  port = 9090 
  autoLaunch = false
  functionsPort = 9091

Environment

  System:
    OS: Linux 5.15 KDE neon 5.25
    CPU: (16) x64 11th Gen Intel(R) Core(TM) i7-11800H @ 2.30GHz
    Memory: 9.52 GB / 15.35 GB
    Container: Yes
    Shell: 5.0.17 - /bin/bash
  Binaries:
    Node: 17.6.0 - ~/apps/nodejs/node-current/bin/node
    Yarn: 1.22.17 - ~/apps/nodejs/node-current/bin/yarn
    npm: 8.5.2 - ~/apps/nodejs/node-current/bin/npm
  npmGlobalPackages:
    netlify-cli: 10.5.1

[danez]

Would you be able to create a small reproduction example? So we can look at it?

[kyllerss]

Hmm... I was unable to reproduce the issue with the latest release. All good now!

[kyllerss]

Sadly the issue seems to have returned. I have more information and a minimal reproduction of the issue. What I am observing is that a post request is being directed to the background job instead of the POST handler to which it was intended.

Here is the minimal reproduction: https://github.com/kyllerss/netlify-issue-4873

The README.md contains the reproduction instructions plus some log samples.

The port I'm using for the app is 4003. The port I am using for the background jobs is 4004. The background job is an empty file, but that doesn't matter (I have content in my original project). The existence of the background job file seems to cause the issue regardless of its contents.

Here is the log for the connection attempt to the background function's port:

...
HTTP 96144: createConnection 127.0.0.1:4004: [Object: null prototype] {
  port: '4004',
  host: '127.0.0.1',
  hostname: '127.0.0.1',
  socketPath: undefined,
  pfx: undefined,
  key: undefined,
  passphrase: undefined,
  cert: undefined,
  ca: undefined,
  ciphers: undefined,
  secureProtocol: undefined,
  method: 'POST',
  headers: {
    'x-forwarded-for': '::1',
  ...

[tinfoil-knight]

@kyllerss Creating a submission-created.ts or submission-created-background.ts file to handle form submissions should fix your issue.

[tinfoil-knight]

@danez I couldn't find any documentation or help articles on how to setup form submission handlers in Netlify CLI. If some documentation exists, could you point me to it?

The only thing I found was this piece of code:

cli/src/lib/functions/form-submissions-handler.mjs

Lines 12 to 16 in 0929141

	const getFormHandler = function ({ functionsRegistry }) {
	const handlers = ['submission-created', `submission-created${BACKGROUND}`]
	.map((name) => functionsRegistry.get(name))
	.filter(Boolean)
	.map(({ name }) => name)

[walker-tx]

Howdy! Bump on this one! I've made a reproduction repo!!

https://github.com/wlockiv/repro-sveltekit-netlify-dev-fn-not-found

Please please let me know what additional info, if any, I can bring to the table! Thank you very much for what you do for our community!

[walker-tx]

Some additional thoughts on this one. It looks like the CLI is taking those post requests and routing them to /.../endpoint/index.htm - it's adding the /index.htm at the end of the url that should be posted to. So yea it should be expected for that to 404. I (naively) attempted the same POST to the sveltekit (non-netlify) dev server and it yielded the same 404.