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.
Showing 16-30 of 62.
HTTP 301 Moved Permanently means the resource has a new permanent URI and future requests should use it.
HTTP 302 Found means the resource is temporarily at a different URI and clients should follow Location for now.
HTTP 303 See Other means the server directs the client to retrieve another resource, usually with GET.
HTTP 304 Not Modified means conditional request found that the cached representation is still valid.
HTTP 305 Use Proxy is deprecated and should not be generated in modern HTTP systems.
HTTP 307 Temporary Redirect means the resource is temporarily elsewhere and request method must be preserved.
HTTP 308 Permanent Redirect means resource moved permanently and redirect must preserve request method and body.
HTTP 400 Bad Request means the server cannot process the request because syntax, framing, or parameters are invalid.
HTTP 401 Unauthorized means the origin or gateway could not authenticate this request and is asking the client to present valid credentials for the target resource.
HTTP 402 Payment Required is reserved for future use in the standard and is usually provider-specific in practice.
HTTP 403 Forbidden means the server understood the request and often knows who the caller is, but policy or business rules still block this action on the target resource.
HTTP 404 Not Found means the server has no current representation for the requested URI at this path, version, tenant, or lifecycle state.
HTTP 405 Method Not Allowed means the resource exists but does not support the HTTP method used.
HTTP 406 Not Acceptable means the server cannot produce a representation matching proactive negotiation headers.
HTTP 407 Proxy Authentication Required means the client must authenticate with a proxy before the request can proceed.