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A Next.js chunk-load error means the browser could not fetch or use a JavaScript chunk required by the page. The message alone does not identify the cause. Start with the failed Network request, then trace its URL and response through the asset origin, deployment, CDN, and—if you run several servers—the instance that handled the request.
1. Inspect the failed chunk request
- Open your browser’s developer tools and select the Network tab.
- Reproduce the failure and find the JavaScript request that failed.
- Record its full URL, status code, response body, response headers, and origin. Confirm whether that origin is the one your application is supposed to use.
Use the response as evidence, not as a diagnosis by itself. A 404 can mean that the page references a chunk no longer available from that asset origin. An HTML error page returned for a JavaScript URL can point to proxy, CDN, or routing behavior. Check the request and the deployment state before choosing a fix.
2. Confirm the asset origin and assetPrefix
If your static JavaScript or CSS files are served from a separate domain or CDN, verify that the requested URL matches your configured assetPrefix and that the chunk exists at that origin. Next.js documents assetPrefix for serving static assets from a CDN or another domain. A correct application build cannot fetch a file that is missing or misrouted at the configured asset origin.
3. Check CDN caching by response type
Do not treat all Next.js responses as interchangeable cache objects. The CDN guide documents content-hashed static assets under /_next/static/ with public,max-age=31536000,immutable—a one-year cache policy for those versioned files. That policy does not make HTML or every deployment artifact immutable. See the Next.js CDN caching guide.
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Static assets
Check that the CDN can retrieve the requested hashed file and is applying the intended cache behavior. If the browser requests a chunk that is absent at the origin, investigate the deployed asset set and the page that referenced it rather than merely extending the cache duration.
HTML and App Router responses
App Router responses can vary according to request headers. A CDN must preserve the cache-key distinctions needed for the response, including relevant RSC and router-state variations. The Next.js guide describes _rsc as a cache-key mechanism for relevant variations. If cache keys collapse distinct requests into one entry, a CDN can return the wrong response variant.
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Revalidation and CDN purges
Next.js server-cache revalidation does not automatically purge a separate CDN cache. If an immediate update is required, coordinate the Next.js revalidation with a CDN purge for the affected keys, including relevant HTML and RSC variants. Otherwise, the CDN may keep serving its cached copy until its configured lifetime ends. A purge can remove a stale response; it does not explain why incompatible content was served, so investigate the cache key and deployment as well.
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4. Check deployment consistency across instances
During a rolling deployment or when running multiple application instances, check which version served the page and whether its referenced chunk is available from the asset origin used by the browser. The page response and its chunks need to remain compatible during the transition; inspect how your deployment architecture publishes and retains assets rather than assuming the framework handles every transition the same way.
For self-hosted deployments, Next.js documents that caches are local to each instance by default. When multiple instances need consistent invalidation, its guidance recommends a shared cache and tag coordination. See self-hosting Next.js and Incremental Static Regeneration. If requests can reach instances on different deployment states, compare which instance served the page with the version and asset set available for the requested chunk.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.5. Reproduce and validate the fix
- Run
next buildto create a production build. - Run
next startand reproduce the affected route in that production-like setup. - After deployment, request the same asset URL that failed and inspect its status, response body, headers, and origin in the actual affected environment.
- Verify that the page response, CDN cache behavior, and active deployment all point to a compatible asset set.
The Next.js production checklist recommends these commands for checking a production build. A successful local reproduction is useful but does not establish that the production origin or CDN is serving the same files and response variants.
Quick Recap
Choose the fix that matches the evidence
| What you find | What to investigate | Likely corrective action |
|---|---|---|
| Requested chunk is missing at the URL’s origin | Asset publication, assetPrefix, and whether the page came from an older deployment |
Restore or correctly serve the referenced asset, and ensure the page and asset set remain compatible during deployment. |
| JavaScript URL returns an HTML error or unexpected response | CDN, proxy, and routing rules for the requested path | Correct the route or response behavior so the asset URL resolves to the intended JavaScript file. |
| Different requests receive an inappropriate cached response | CDN cache keys for HTML and App Router/RSC variations | Preserve the relevant request distinctions in cache keys; purge affected entries when necessary. |
| Instances behave differently after revalidation or deployment | Per-instance cache state and invalidation coordination | Evaluate shared cache and tag coordination for the multi-instance setup. |
Prevent recurrence and improve detection
- Keep deployment procedures aligned with the way your page responses and static assets are published and retained.
- Review CDN cache keys and response variation before changing cache durations; hashed static files and HTML/RSC responses have different caching concerns.
- For multi-instance self-hosting, assess shared cache and tag coordination where consistent invalidation is required.
- Use production error handling and monitoring to observe failures and help users recover. The production checklist also discusses a global error UI and sending Web Vitals to analytics; these practices improve observability or recovery, but do not restore a missing chunk.
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