SvelteKit 2.21.3 Breaks Certain CommonJS Packages in Production

[abdelfattahradwan]

Describe the bug

After upgrading to SvelteKit 2.21.5 from SvelteKit 2.21.2, I am starting to get ReferenceError: require is not defined in ES module scope whenever I import a package that uses require in any capacity. This did not happen before SvelteKit 2.21.3.

I thought it might be an issue with specific packages or projects, but it's not. I tested three different projects, all with different dependencies, and the same problem occurred.

Examples of affected packages:

• marked (https://www.npmjs.com/package/marked)
• highlight.js (https://www.npmjs.com/package/highlight.js)
• @google/genai (https://www.npmjs.com/package/@google/genai)
• nodemailer (https://www.npmjs.com/package/nodemailer)

I concluded that the issue is caused by SvelteKit versions >= 2.21.3 because I kept downgrading, and once I went below 2.21.3, things worked as expected.

Reproduction

• Create a new SvelteKit project
• Install one or more of the packages mentioned above
• Import one or more of them in a server module (e.g. +page.server.ts, code inside a .server.ts file, or files inside the $lib/server directory)
• Build your app
• Run the app and execute any code that would cause the module to be loaded

Logs

ReferenceError: require is not defined in ES module scope, you can use import instead
This file is being treated as an ES module because it has a '.js' file extension and '[REDACTED_PATH]/package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.
    at ExportsCache.has (file://[REDACTED_PATH]/build/server/chunks/hooks.server-MojicEX3.js:15490:20)
    at Module.patchedRequire (file://[REDACTED_PATH]/build/server/chunks/hooks.server-MojicEX3.js:15618:22)
    at Hook._require.Module.require (file://[REDACTED_PATH]/build/server/chunks/hooks.server-MojicEX3.js:15557:28)
    at require (node:internal/modules/helpers:135:16)
    at Object.<anonymous> ([REDACTED_PATH]/node_modules/highlight.js/lib/index.js:1:12)
    at Module._compile (node:internal/modules/cjs/loader:1730:14)
    at Object..js (node:internal/modules/cjs/loader:1895:10)
    at Module.load (node:internal/modules/cjs/loader:1465:32)
    at Function._load (node:internal/modules/cjs/loader:1282:12)
    at TracingChannel.traceSync (node:diagnostics_channel:322:14)

System Info

System:
    OS: Windows 11 10.0.26100
    CPU: (28) x64 Intel(R) Core(TM) i7-14700K
    Memory: 35.78 GB / 63.70 GB
  Binaries:
    Node: 22.16.0 - C:\Program Files\nodejs\node.EXE
    npm: 11.4.1 - ~\AppData\Roaming\npm\npm.CMD
    bun: 1.2.16 - ~\.bun\bin\bun.EXE
  Browsers:
    Edge: Chromium (137.0.3296.68)
    Internet Explorer: 11.0.26100.1882
  npmPackages:
    @sveltejs/adapter-node: ^5.2.12 => 5.2.12
    @sveltejs/kit: ^2.21.5 => 2.21.5
    @sveltejs/vite-plugin-svelte: ^5.1.0 => 5.1.0
    svelte: ^5.34.2 => 5.34.2
    vite: ^6.3.5 => 6.3.5

Severity

blocking an upgrade

Additional Information

No response

[elliott-with-the-longest-name-on-github]

Hmm @eltigerchino is this another downstream of the bundling change? It appears like we're loading a cjs version when we're expecting an esm version -- for example, marked exports both but we wouldn't expect to see this error if we were loading the esm one...

[yaman-cruise]

I can confirm this issue with the package @sentry/sveltekit.

[teemingc]

I've tested with marked and highlight.js and can't seem to reproduce this. Can you please share a minimal reproduction so that we can know the exact conditions this bug occurs in?

Hmm @eltigerchino is this another downstream of the bundling change? It appears like we're loading a cjs version when we're expecting an esm version -- for example, marked exports both but we wouldn't expect to see this error if we were loading the esm one...

It should be related to https://github.com/sveltejs/kit/pull/13843/files#diff-beef34c36ed87d7835d0166655010910fba9949a6ef95042cb468d7d73423816 but that only bundles packages that declare a dependency on @sveltejs/kit.

We had this issue with @sentry/sveltekit a week ago #13869 but that was due to their exports field pointing to the CJS version under the node condition, so we managed to fix that upstream. Even then, it was only bundled because it had a peer dep on kit, which none of these packages seem to have.

[abdelfattahradwan]

@eltigerchino Unfortunately, I am also unable to reproduce the issue in a clean, new SvelteKit project. However, I have two larger projects that exhibit the same problem described above. Is there a way to privately share one of them with you to avoid leaking the contents to the public?

[abdelfattahradwan]

I found the cause. It is because of both @sveltejs/kit (>= 2.21.3) and @sentry/sveltekit.

I had the following code in hooks.client.ts:

import * as Sentry from "@sentry/sveltekit";
import { handleErrorWithSentry } from "@sentry/sveltekit";

Sentry.init({
  dsn: "[REDACTED]",
  tracesSampleRate: 1.0,
  enabled: import.meta.env.PROD,
});

export const handleError = handleErrorWithSentry();

And this code in hooks.server.ts:

import * as Sentry from "@sentry/sveltekit";
import { sequence } from "@sveltejs/kit/hooks";
import { handleErrorWithSentry, sentryHandle } from "@sentry/sveltekit";

Sentry.init({
  dsn: "[REDACTED]",
  tracesSampleRate: 1.0,
  enabled: import.meta.env.PROD,
});

export const handle = sequence(sentryHandle());

export const handleError = handleErrorWithSentry();

After I commented those out, I was able to build and run my application normally without encountering the errors reported in the original message.

For some reason, SvelteKit versions after 2.21.3 don't play nicely with @sentry/sveltekit (or the other way around?).

The reason I wasn't able to reproduce the issue is that the reproduction project didn't use @sentry/sveltekit. After adding it to the reproduction project, I began to encounter the same errors.

[Cluster2a]

Same problem here (svelteKit + sentry).

[teemingc]

What version of @sentry/sveltekit are you using? This should have been fixed in https://github.com/getsentry/sentry-javascript/releases/tag/9.28.1 but there may be remaining issues causing the CJS version of Sentry to be bundled instead. Possibly related: getsentry/sentry-javascript#16586

[jeannemas]

I also encounter the issue, but my logs seems to indicate that it's related to chokidar this time.

Dependency	Version
@sentry/sveltekit	9.29.0
@sveltejs/kit	2.21.5

It is interesting to note, that chokidar is not one of my dependencies, it is a dependency of one of my dependencies.

Staying on @sveltejs/kit@2.21.2 is the only way I've found to avoid the issue.

✗ Build failed in 10.92s
error during build:
[commonjs--resolver] ../../node_modules/.pnpm/fsevents@2.3.3/node_modules/fsevents/fsevents.node (1:0): Unexpected character '�' (Note that you need plugins to import files that are not JavaScript)
file: /REDACTED/node_modules/.pnpm/fsevents@2.3.3/node_modules/fsevents/fsevents.node:1:0 (/REDACTED/node_modules/.pnpm/chokidar@3.6.0/node_modules/chokidar/index.js)

1: ����@<�
                              ��*...
   ^
4* 
                      h���/System/Library/Frameworks/CoreFoundation.framework/Versions...
3: ���H��1�H���L���L���H�����L�E�L��H��1�����uH�E�H�[A^A_]��}f.�UH��AWAVSPI��H��I��H�H...

    at getRollupError (file:///REDACTED/node_modules/.pnpm/rollup@4.42.0/node_modules/rollup/dist/es/shared/parseAst.js:401:41)
    at ParseError.initialise (file:///REDACTED/node_modules/.pnpm/rollup@4.42.0/node_modules/rollup/dist/es/shared/node-entry.js:14293:28)
    at convertNode (file:///REDACTED/node_modules/.pnpm/rollup@4.42.0/node_modules/rollup/dist/es/shared/node-entry.js:16197:10)
    at convertProgram (file:///REDACTED/node_modules/.pnpm/rollup@4.42.0/node_modules/rollup/dist/es/shared/node-entry.js:15440:12)
    at Module.setSource (file:///REDACTED/node_modules/.pnpm/rollup@4.42.0/node_modules/rollup/dist/es/shared/node-entry.js:17185:24)
    at async ModuleLoader.addModuleSource (file:///REDACTED/node_modules/.pnpm/rollup@4.42.0/node_modules/rollup/dist/es/shared/node-entry.js:21187:13)
 ELIFECYCLE  Command failed with exit code 1.
ERROR: command finished with error: command (/REDACTED/apps/website) ~/Library/pnpm/.tools/pnpm/10.12.1/bin/pnpm run build exited (1)

[teemingc]

We really need a minimal reproduction (in the form of a downloadable repository) because I can't reproduce this by installing marked and @sentry/sveltekit.

[yaman-cruise]

It's not enough to install the packages. You also have to import them to a server file e.g. hooks.server.ts. Here is a minimal repo that creates the error: https://github.com/yaman-cruise/svelte-sentry

1. run pnpm build and you'll get the error

[teemingc]

It's not enough to install the packages. You also have to import them to a server file e.g. hooks.server.ts.

Yes, I've installed them and imported them into a server file.

Here is a minimal repo that creates the error: yaman-cruise/svelte-sentry

1. run `pnpm build` and you'll get the error

This doesn't error for me after running pnpm build. Which Node version and operating system are you using when running the build? I'm running on WSL 2 Ubuntu 22.04.5 LTS and Node v18.20.8