HTTP Status Code Reference for APIs, websites, proxies, and debugging

100 Continue means the server has received the initial part of the request, usually the request line, request headers, and enough metadata to make an early decision, and it has not found a reason to reject the request yet. It is an informational, interim response; it does not mean the request has succeeded. Its main purpose is to tell the client that it may continue sending the remaining request content, especially a large request body. It is most commonly used with the Expect: 100-continue mechanism, where the client sends headers first, waits for the server to perform early checks such as authentication, permissions, Content-Type, Content-Length, and resource limits, and then sends the body only after receiving permission to continue. The final result is still determined by a later final response status code.

101 Switching Protocols means the server understood the client's protocol upgrade request, usually expressed with the Upgrade header, and agrees to switch the current connection to another protocol. It is an informational response used during a protocol upgrade handshake, not a normal success response for returning business data. After 101 is sent, subsequent bytes on the same connection are interpreted according to the protocol named in the Upgrade response header instead of the original HTTP message format. The most common example is the WebSocket handshake: the client starts with an HTTP request, the server validates Upgrade, Connection, and WebSocket headers, returns 101, and the connection becomes a bidirectional WebSocket channel.

102 Processing means the server has received the complete request and is working on it, but no final response is available yet. It originally came from WebDAV and was intended for operations that may take a long time, such as multi-resource file operations. Its purpose is to reassure the client that the request was not lost and that the server is still processing it. 102 is not a final response and does not mean success. It was defined in RFC 2518 and later removed from the updated WebDAV specification, so modern general-purpose web services rarely send it intentionally.

103 Early Hints lets the server send headers that are likely to appear in the final response before the final response itself is ready. It is mainly a performance optimization, not a business result. The most common use is sending Link headers early while the server is still generating HTML, waiting on a database, rendering a page, or calling an upstream service. A browser can then preconnect, preload, or prefetch critical resources such as CSS, JavaScript, fonts, images, or third-party origins. 103 does not replace the final response; the client must still wait for the final status code.

104 Upload Resumption Supported tells the client, during an upload request, that the target resource supports HTTP upload resumption. It is an informational status code for resumable upload scenarios and is currently a temporary registration tied to an HTTP draft, not a stable RFC. Its purpose is not to say that the upload succeeded; it tells the client that if the upload is interrupted by a network failure, tab close, connection reset, or mobile network switch, the client may later resume according to the protocol instead of starting from scratch.

200 OK means that the server successfully processed the request and returned a response appropriate to the method. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

201 Created means that the request succeeded and the server created a new resource as a result. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

202 Accepted means that the server accepted the request for processing, but the final outcome is not available yet. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

203 Non-Authoritative Information means that the response is successful but differs from the origin's authoritative representation because an intermediary modified it. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

204 No Content means that the server successfully completed the request and intentionally has no content to send in the response body. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

205 Reset Content means that the operation succeeded and the user agent is expected to reset the document view, form, or input state. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

206 Partial Content means that the response contains one or more ranges of the target resource instead of the complete representation. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

207 Multi-Status means that the server is returning a multi-part status report, usually for WebDAV operations across multiple resources. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

208 Already Reported means that the response is avoiding duplicate reporting of the same WebDAV binding member. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

226 IM Used means that the server satisfied a GET request using delta encoding or another instance manipulation supported by the client. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

300 Multiple Choices means that the request matches more than one representation and the user or client may need to choose. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

301 Moved Permanently means that the target resource has a new permanent URI and clients or search engines may update stored references. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

302 Found means that the client may temporarily use another URL, but future requests should still use the original URL. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

303 See Other means that the result of the request can be found at another URI, and the client should use GET for that URI. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

304 Not Modified means that the conditional request matched the current resource state, so the client may use its cached copy. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

305 Use Proxy means that the requested response must be accessed through a proxy, but this mechanism is obsolete and unsafe for modern use. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

306 Unused means that there is no active meaning assigned to this code today. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

307 Temporary Redirect means that the client should repeat the same request method and body at the temporary Location. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

308 Permanent Redirect means that the client should use the new URI permanently while preserving the original request method. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

400 Bad Request means that the server cannot understand or process the request because of invalid syntax, malformed JSON, invalid parameters, or bad framing. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

401 Unauthorized means that the request lacks valid authentication credentials for the target resource. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

402 Payment Required means that the request cannot be fulfilled without payment or commercial entitlement, but the standard does not define a universal payment flow. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

403 Forbidden means that the requester is not allowed to perform the operation, even if the request is syntactically valid. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

404 Not Found means that the requested URL, route, resource ID, or endpoint does not exist from the caller's perspective. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

405 Method Not Allowed means that the target resource is known, but the HTTP method is not allowed for it. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

406 Not Acceptable means that the client's Accept-related headers require a response format, language, charset, or encoding the server cannot provide. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

407 Proxy Authentication Required means that a proxy server, not the origin server, requires authentication. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

408 Request Timeout means that the client did not send the full request quickly enough, or the connection stayed idle too long before completion. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

409 Conflict means that the server cannot complete the request because it would conflict with resource state, versioning, uniqueness, or concurrency rules. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

410 Gone means that the target resource is intentionally and permanently gone. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

411 Length Required means that the request has a body or expected body but does not provide the required length information. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

412 Precondition Failed means that a conditional request failed, often because the client's resource version is stale. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

413 Content Too Large means that the request body or uploaded content exceeds server, gateway, framework, or policy limits. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

414 URI Too Long means that the URL, path, or query string is too long. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

415 Unsupported Media Type means that the server refuses the request because Content-Type, Content-Encoding, or uploaded format is unsupported. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

416 Range Not Satisfiable means that the Range header asks for a portion of the resource that is invalid or outside the available representation. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

417 Expectation Failed means that the server or an intermediary cannot meet the client's Expect header requirements. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

418 I'm a teapot means that the server is, humorously, a teapot and refuses to brew coffee. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

419 Page Expired is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Laravel or a web framework convention. It usually indicates that the page session, login session, or CSRF token has expired. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

420 Enhance Your Calm is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Twitter legacy API convention. It usually indicates that the client is sending too many requests or behaving aggressively. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

421 Misdirected Request means that the connection or routing layer delivered the request to the wrong authoritative server. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

422 Unprocessable Content means that the server understands the request format, but the submitted values or business rules cannot be processed. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

423 Locked means that the requested resource is locked, often in WebDAV or collaborative editing contexts. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

424 Failed Dependency means that a dependent action in the same WebDAV or batch operation did not succeed. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

425 Too Early means that the request may have been sent as TLS early data, and replaying it could be unsafe. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

426 Upgrade Required means that the server refuses the request under the current protocol but may accept it after an upgrade. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

428 Precondition Required means that the server requires precondition headers to prevent lost updates or unsafe overwrites. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

429 Too Many Requests means that the server is rate limiting the client, user, IP, tenant, API key, or route. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

430 Request Header Fields Too Large is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with a non-standard platform convention. It usually indicates that request headers are too large or rejected by a platform-specific rule. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

431 Request Header Fields Too Large means that the server refuses the request because headers are too large individually or in total. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

440 Login Time-out is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Microsoft IIS or Exchange ecosystem. It usually indicates that the login session timed out and the user must authenticate again. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

444 No Response is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Nginx. It usually indicates that Nginx closed the connection without sending a response. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

449 Retry With is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Microsoft IIS extension. It usually indicates that the request needs additional information before retrying. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

450 Blocked by Windows Parental Controls is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Microsoft or Windows ecosystem. It usually indicates that access was blocked by Windows parental-control-like policy. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

451 Unavailable For Legal Reasons means that the server cannot provide the resource because access is blocked for legal reasons. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

460 Client Closed Connection is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with AWS Elastic Load Balancing. It usually indicates that the client closed the connection before the load balancer returned a response. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

463 Too Many IP Addresses is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with AWS Elastic Load Balancing. It usually indicates that forwarded IP headers contain too many addresses. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

464 Incompatible Protocols is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with AWS Elastic Load Balancing. It usually indicates that the client, load balancer, and target group protocols are incompatible. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

494 Request Header Too Large is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Nginx. It usually indicates that Nginx rejected the request because headers were too large. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

495 SSL Certificate Error is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Nginx. It usually indicates that Nginx encountered an error while validating the client certificate. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

496 SSL Certificate Required is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Nginx. It usually indicates that Nginx required a client certificate but none was provided. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

497 HTTP Request Sent to HTTPS Port is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Nginx. It usually indicates that plain HTTP was sent to an HTTPS port. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

498 Invalid Token is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Esri ArcGIS or a custom API convention. It usually indicates that a token is invalid, expired, or not accepted. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

499 Client Closed Request is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Nginx. It usually indicates that the client closed the request before the server responded. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

500 Internal Server Error means that the server failed while processing the request and does not have a more specific 5xx response. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

501 Not Implemented means that the server lacks support for the method, feature, or protocol capability needed by the request. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

502 Bad Gateway means that an intermediary could not get a valid HTTP response from the upstream service. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

503 Service Unavailable means that the server is overloaded, under maintenance, temporarily unavailable, or protecting itself. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

504 Gateway Timeout means that an intermediary connected to an upstream service but did not receive a timely response. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

505 HTTP Version Not Supported means that the client used an HTTP version the server refuses or cannot support. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

506 Variant Also Negotiates means that the selected variant resource is itself configured to perform negotiation, causing a negotiation problem. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

507 Insufficient Storage means that the server cannot store the representation needed to complete the operation. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

508 Loop Detected means that the server found an infinite loop in resource bindings or traversal. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

509 Bandwidth Limit Exceeded is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Apache/cPanel hosting convention. It usually indicates that the site or account exceeded a bandwidth quota. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

510 Not Extended means that the server expects extension information from an old HTTP extension framework. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

511 Network Authentication Required means that network access authentication is required before normal internet access is available. A useful response should let the HTTP status code describe the protocol-level result, while the response body can carry a stable application error code, field-level validation details, trace ID, retry instruction, or documentation link.

520 Web Server Returned an Unknown Error is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare. It usually indicates that Cloudflare received an empty, unknown, or unclassifiable response from the origin. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

521 Web Server Is Down is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare. It usually indicates that Cloudflare cannot connect to the origin web server. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

522 Connection Timed Out is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare. It usually indicates that Cloudflare timed out while connecting to the origin. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

523 Origin Is Unreachable is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare. It usually indicates that Cloudflare cannot reach the origin network. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

524 A Timeout Occurred is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare. It usually indicates that Cloudflare connected to the origin but did not receive an HTTP response in time. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

525 SSL Handshake Failed is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare. It usually indicates that Cloudflare could not complete a TLS handshake with the origin. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

526 Invalid SSL Certificate is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare. It usually indicates that Cloudflare could not validate the origin certificate. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

527 Railgun Error is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare Railgun. It usually indicates that Cloudflare Railgun encountered an origin connection or protocol error. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

530 Origin DNS Error is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Cloudflare. It usually indicates that Cloudflare cannot resolve the origin hostname or has an origin DNS problem. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

561 Unauthorized is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with AWS Elastic Load Balancing. It usually indicates that AWS load balancer authentication failed or could not complete. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

598 Network Read Timeout Error is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Proxy / Gateway convention. It usually indicates that a proxy or client timed out while reading the upstream response. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.

599 Network Connect Timeout Error is not an IANA-registered standard HTTP status code. It is a non-standard code or implementation-specific extension associated with Proxy / Gateway convention. It usually indicates that a proxy or client timed out while connecting to upstream. However, they should not be treated as portable REST API contracts. Different browsers, HTTP clients, monitoring tools, crawlers, and intermediaries may not understand them consistently.