Our HTTP reference library maps each status code to standards-based semantics and real remediation paths for API and web teams. Every page clarifies when a response is expected, when it signals a defect, and how to verify the fix in production traffic.
These are the highest-signal HTTP pages for common production failures and the best first routes for internal linking and early user navigation.
Priority guide
Internal Server Error
Fix HTTP 500 by correlating stack traces, release changes, and dependency health to isolate deterministic code bugs, config drift, or late-translated...
->Priority guide
Too Many Requests
Fix HTTP 429 by tracing limiter dimensions, Retry-After behavior, and client backoff design to stop retry storms and quota spikes.
->Priority guide
Unauthorized
Fix HTTP 401 by tracing WWW-Authenticate challenges, bearer token claims, session cookies, and proxy header forwarding on the exact failing route.
->Priority guide
Forbidden
Fix HTTP 403 by tracing authenticated identity, denied action, resource scope, and explicit policy or WAF blocks for the exact route.
->Priority guide
Not Found
Fix HTTP 404 by validating route version, resource ID, tenant scope, and stale links before changing application logic.
->When you need broader context, move from provider-specific pages into the matching error category or incident playbook before changing production behavior.
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HTTP 510 Not Extended is an obsolete status code from an experimental extension model and should not be emitted by modern HTTP APIs.
HTTP 511 Network Authentication Required means the client must authenticate to gain network access, often through a captive portal.