ChunkLoadError: Loading chunk 123 failed.
A lazily loaded JavaScript chunk couldn’t be downloaded — usually because a new deployment removed the old hashed files.
Loading chunk failedFailed to fetch dynamically imported moduleLoading CSS chunk failed Meaning
Users with an open tab still reference old chunk filenames. After deploy those files are gone (404), so dynamic imports fail. Network blips and ad blockers can also cause it.
Common causes
- New deploy deleted old hashed chunks
- CDN/cache serving stale index.html
- Network failure
- Wrong publicPath/base for chunks
⚡ Quick fix
- Keep previous build assets for a while after deploys
- Catch the error and reload the page once
- Set publicPath/base correctly
Detailed fix by platform
JavaScript
window.addEventListener('vite:preloadError', () => window.location.reload());
How to diagnose
- Chunk URL — Does it 404?
- Timing — Right after a deploy?
🔧 Still not fixed?
Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:
Similar errors
- App Service Application Error Azure App Service: ":( Application Error" / container didn’t respond to HTTP pings
- Can't resolve 'fs' Module not found: Can't resolve 'fs' (Next.js / webpack 5)
- DevTools failed to load source map DevTools: Failed to load source map — Could not load content for https://…/app.js.map: HTTP error: status code 404
Most viewed in JavaScript
Other ways to find it
Where this error sits
Origin: On your device. Errors that are often confused with or caused by this one (click to open):
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Last updated 9 Oct 2026