EngineeringScoreFix failed network requests
A request that comes back 4xx or 5xx, or that never reaches a server at all, means something the page depends on (an API call, an image, a script, a font) failed to load. Depending on what failed, the visible impact ranges from a missing icon to an entire feature (like checkout or search) silently not working. The two shapes usually have different causes: an error status means the server answered and refused, while a connection that never opened points at a hostname that no longer resolves, a service that is down, or a certificate the browser rejected.
Why it matters
A request that returns 4xx/5xx, or that never reaches a server at all, means something the page depends on (an API, an image, a script) is not arriving, which can silently degrade or break the user experience.
How to fix
- 1 Identify which requests are failing and how (check the network tab and server logs: an error status points at the application, a connection or DNS failure points at the hostname, certificate, or the service being down).
- 2 Fix broken URLs, missing assets, unresolvable hostnames, or backend errors causing the failures.
- 3 Add alerting so new failures are caught quickly.
Common mistakes
- Fixing the specific failing URL without checking whether the same root cause (a renamed endpoint, an expired API key, a retired subdomain) affects other requests too.
- Treating a 404 on a non-critical asset as low priority without checking whether it is actually a broken dependency for a feature (a missing font can degrade legibility across the whole site).
- Not distinguishing between transient failures (a flaky third-party API) and a persistent broken reference, which need different fixes.
How to verify
- 1 Open devtools network panel, reload the page, and exercise key flows while checking both for 4xx/5xx responses and for requests that show as failed with no status at all.
- 2 Check server/application logs for the same time window to correlate client-visible failures with backend errors, and confirm every hostname the page requests still resolves and serves a valid certificate.
- 3 Add alerting on error-rate spikes so new failures are caught quickly rather than discovered by users.
Related checks
Ready to see where you stand?
Scan your site and get your Engineering Score with a prioritized roadmap in under a minute, no signup required.