Why can Angular navigation work locally but a production deep link return 404?

Diagnoses server fallback rules, deployment base paths, asset URLs, and cache behavior rather than changing Angular routes blindly.

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TL;DR

A local development server usually falls back to the Angular entry document, but a production server may look for a physical file at the route and return 404. I configure a fallback to index.html for application routes while preserving real API, asset, and error responses. If the app is hosted below the origin root, I also verify its base href and generated asset URLs.

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Angular deployment, SPA rewrites, deep links, base href, asset paths, reverse proxies, and HTTP diagnostics.

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Core answer
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Overview
Client navigation stays inside the running application, while a direct URL is first resolved by the server or CDN.
A local development server usually falls back to the Angular entry document, but a production server may look for a physical file at the route and return 404. I configure a fallback to index.html for application routes while preserving real API, asset, and error responses. If the app is hosted below the origin root, I also verify its base href and generated asset URLs.
Checkpoint
Stronger answer
Optional upgrade with examples, trade-offs, and sharper phrasing.
I test refresh and direct entry on a nested route through the real CDN or reverse proxy, not only client-side clicks. The fallback must not convert missing JavaScript, images, API paths, or genuine server errors into HTML with a 200 response. I inspect the network response, content type, base element, and lazy-chunk URLs before changing Router configuration. Redirect and authentication callbacks are included because their query and fragment data must survive.

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Common mistakesCandidateCommon mistakesMistakes that weaken the answer or signal shallow understanding.Open details

Details

Changing Angular route definitions when the server never served the application.
Rewriting every 404, including missing assets and API routes, to index.html.
Ignoring base href when deploying under a subpath.

Why can Angular navigation work locally but a production deep link return 404?

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