🐛 BUG: sveltekit quickstart gives a 500 server error - 'No such module "node:async_hooks"'

[filipe-freire]

Which Cloudflare product(s) does this pertain to?

Pages

What version(s) of the tool(s) are you using?

3.91.0 [Wrangler], 9.13.2 [pnpm]

What version of Node are you using?

22.11.0

What operating system and version are you using?

Linux (Pop!_OS jammy 22.04 x86_64) | Kernel: Linux 6.9.3-76060903-generic

Describe the Bug

Observed behavior

Upon running the step to jumpstart a new sveltekit project through the CLI shown in the Cloudflare website, all appears to run smoothly (with no errors on the terminal) up until the "DNS propagation/waiting for the deployment to become available" step.

Right after "DNS propagation complete." the terminal outputs timed out while waiting for https://<project-name>.pages.dev - try accessing it in a few minutes..

Upon waiting +30min, the page is still showing a 500 Internal Server Error.
Inspecting the cloudflare pages logs show an error: ` No such module "node:async_hooks"

My best guess is that some 3rd party library integration is requiring that module causing it to show, since choosing a simple sveltekit app with no integrations does not cause the error and the deployment goes through without issue. I'll update the issue with my findings.

Expected behavior

The CFPages project should deploy successfully without any errors.

Steps to reproduce

• Run the command shown in the CF docs to quicktstart & deploy a SvelteKit project to CFPages: pnpm create cloudflare@latest my-svelte-app --framework=svelte

Chosen CLI options:

Which template would you like?
│  SvelteKit minimal
│
◇  Add type checking with Typescript?
│  Yes, using Typescript syntax
│
◆  Project created
│
◇  What would you like to add to your project? (use arrow keys / space bar)
│  prettier, eslint, vitest, tailwindcss, drizzle, paraglide, playwright
│
◇  tailwindcss: Which plugins would you like to add?
│  typography, forms
│
◇  Which package manager do you want to install dependencies with?
│  pnpm

Please provide a link to a minimal reproduction

No response

Please provide any relevant error logs

The redacted error log shown in the CFPages dashboard for the project:

{
  "truncated": false,
  "executionModel": "stateless",
  "outcome": "ok",
  "scriptVersion": {
    "id": "c5af4521-516a-41e3-899e-bd075efeed9a"
  },
  "scriptName": "pages-worker--4510812-production",
  "diagnosticsChannelEvents": [],
  "exceptions": [],
  "logs": [
    {
      "message": [
        "Error: No such module \"node:async_hooks\"."
      ],
      "level": "error",
      "timestamp": 1732976236667
    }
  ],
  "eventTimestamp": 1732976236660,
  "event": {
    "request": {
      "url": "https://<project-name>.pages.dev/",
      "method": "GET",
      "headers": {
       ...
      },
      "cf": {
        "httpProtocol": "HTTP/3",
        "tlsCipher": "AEAD-AES128-GCM-SHA256",
        "continent": "EU",
        "asn": 2840,
        "clientAcceptEncoding": "gzip, deflate, br, zstd",
        "country": "SE",
        "isEUCountry": "1",
        "verifiedBotCategory": "",
        "tlsClientAuth": {
          ...
        },
        "tlsExportedAuthenticator": {
          ...
        },
        "botManagement": {
          "corporateProxy": false,
          "verifiedBot": false,
          "jsDetection": {
            "passed": false
          },
          "staticResource": false,
          "detectionIds": {},
          "score": 99
        }
      }
    },
    "response": {
      "status": 500
    }
  },
  "id": 1
}

[filipe-freire]

After some triaging, the issue seems to be due to the package paraglide, as installing the following combination of packages prettier, eslint, vitest, tailwindcss, drizzle seems to not trigger the error, making the deployment go through successfully.

I also found this page, which shows that node:async_hooks is not yet supported by WorderD & Wrangler, although I'm not 100% sure how up-to-date the info is here.

If anyone is more knowledgeable about this issue/domain, please feel free to pitch in :)

[edmundhung]

Thanks for raising this issue, @filipe-freire!

We do have basic support for some APIs from node:async_hooks. Could you check if adding nodejs_als or nodejs_compact to the compatibility_flags config resolves the issue?

[filipe-freire]

Hey @edmundhung, thanks for pitching in!

I assume you meant the flag nodejs_compat? After consulting this page and adding the flag nodejs_compat to my wrangler.toml, the deployment went through successfully! 🎉

If I understand correctly, that flag needs to be added if some specific node internals are used in the app, correct?

If so, maybe it'd be beneficial to add the nodejs_compat flag to the wrangler.toml from the get-go, when scaffolding new apps through the CLI, since as a user, one cannot be sure if external dependencies rely on those node internals or not.

A comment could also be added there explaining the need for such flag in the first place, and referencing the user to the link shared above, in order to provide a smoother deployment experience.

Any thoughts? 😄