Uncaught (in promise) ChunkLoadError: Loading chunk 248 failed.

[zherr]

When using the trackLink method to delay the navigation of a link so that an event may fire to Segment, we experience this error:

Uncaught (in promise) ChunkLoadError: Loading chunk 248 failed.
(error: https://test-website.com/auto-track-d4cf8be594270c3e43e5.js)
    j https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    e https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    e https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    Ue https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    u https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    u https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    u https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    u https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    trackLink https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    ge https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    trackLink https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    trackLink https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    tn https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    tn https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    emit https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    signalSuccess https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    ee https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    initialize https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    promise callback*88453/initialize/< https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    promise callback*88453/initialize/< https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    initialize https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    Vt https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    Jt https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    88453 https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    d https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    79377 https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    d https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    60020 https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    d https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    56498 https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    d https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    <anonymous> https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    O https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    <anonymous> https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    t https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    <anonymous> https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
webpack-runtime-5a0baf3dff035389e835.js:1:8340
    u https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    (Async: promise callback)
    c https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    u https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    u https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    trackLink https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    ge https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    trackLink https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    trackLink https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    tn https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    (Async: EventListener.handleEvent)
    tn https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    emit https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    signalSuccess https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    ee https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    initialize https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    (Async: promise callback)
    initialize https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    (Async: promise callback)
    initialize https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    initialize https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    Vt https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    Jt https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    88453 https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    d https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    79377 https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    d https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    60020 https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    d https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    56498 https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    d https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    <anonymous> https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    O https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    <anonymous> https://test-website.com/app-dd71c1aff3bc61437a9c.js:2
    t https://test-website.com/webpack-runtime-5a0baf3dff035389e835.js:1
    <anonymous> https://test-website.com/app-dd71c1aff3bc61437a9c.js:2

As a result, navigation happens immediately and an event is not fired.

This is happening on SDK version(s):

    "@segment/analytics-next": "^1.81.0",

This appears related to: #348

There is also a suspicious line of code in the method of this library that seems to indicate developers attempting to debug something, or leaving an indication of this issue:

analytics-next/packages/browser/src/core/analytics/index.ts

Lines 384 to 386 in 80ef0be

	const autotrack = await import(
	/* webpackChunkName: "auto-track" */ '../auto-track'
	)

As a workaround, we are having to implement code as follows:

        event.preventDefault()
        const link = document.getElementById('link-id') 

        setTimeout(() => {
          window.location.href = t.href
        }, 3000)

       segment.track(...)

[zherr]

Support ticket: https://segment.zendesk.com/hc/en-us/requests/568349

[silesky]

@zherr

• What is your runtime environment and bundler (chrome extension, browser, etc)?
• trackLink is fairly widely used -- can you provide a repro repo / codesandbox?

There is also a suspicious line of code in the method of this library that seems to indicate developers attempting to debug something.

This is a magic comment.

[zherr]

@zherr

* What is your runtime environment and bundler (chrome extension, browser, etc)?

* trackLink is fairly widely used -- can you provide a repro repo / codesandbox?

There is also a suspicious line of code in the method of this library that seems to indicate developers attempting to debug something.

This is a magic comment.

The browser I'm using is Firefox 138.0.3 (aarch64)

The application runtime is GatsbyJS 5.14.3

Let us know if this is enough for you to help us debug. We can work on a sandbox environment once we have a bit more time internally.

[neelkanth-kaushik]

Hi @zherr ,

Thank you for reporting this issue. We’ve conducted an internal investigation on this issue, and here are our observations:

Reason for the Error

The error you described occurs during the execution of the trackLink() method from Segment’s @segment/analytics-next JavaScript SDK. This method internally performs a dynamic import of the auto-track module.

Root Cause Analysis

The error arises because the browser is unable to fetch the dynamically imported module file (auto-track.[hash].js). This typically happens when:

• The file is missing from the server.
• The reference to the file is incorrect.

In the Segment SDK, the relevant import looks like this:

const autotrack = await import(
  /* webpackChunkName: "auto-track" */ '../auto-track'
);

The trackLink() method is designed to delay navigation until Segment tracking completes. If the import() fails, the event is never tracked. Depending on your error handling, navigation might proceed immediately or inconsistently.

Additional Context on Dynamic Imports

Dynamic imports are not inherently a bad design choice. On the contrary, code splitting is a well-established technique for optimizing bundle size and improving performance.

However, issues can arise when consumers use bundlers that:

• Handle code splitting or chunk generation differently
• Require custom configuration to properly resolve and serve dynamically imported modules

This can lead to situations where expected chunks (like auto-track.[hash].js) are not generated, not served correctly, or are misreferenced—ultimately causing runtime errors.

Verification and Reproduction

We attempted to reproduce the issue, but the SDK worked correctly out of the box with both Parcel and Gatsby, without requiring any custom configuration.

To better understand potential failure scenarios, we conducted a test where we intentionally removed or renamed the auto-track.[hash].js file from the generated dist/ directory (for Parcel) or public/ directory (for Gatsby). This successfully reproduced the exact error you encountered.

Conclusion

The issue is most likely caused by a missing or incorrectly referenced auto-track chunk file in your build output. This could be due to a build misconfiguration, a caching issue, or accidental file deletion.

Recommendation

We recommend reviewing your build setup to ensure that dynamically imported chunks are correctly generated, referenced, and served. This may involve checking custom output paths, caching strategies, or plugin behavior depending on your specific bundler and deployment setup.

To help us investigate further, could you please share the exact steps to reproduce the issue in your environment? Specifically, it would be helpful to know:

1. Any custom configuration related to code splitting or dynamic imports
2. The environment in which the error occurs (e.g., development, production, CI)
3. Any relevant logs, file paths, or screenshots

Thanks.