20.03 HTTP codes cheatsheet

For the wikipedia page, go here.

For a clearer understanding with visuals, go here. Here is an example:

Official HTTP Status Codes

Informational Responses (100–199)

• 100 Continue: The server has received the request headers and the client should proceed to send the request body.

• 101 Switching Protocols: The requester has asked the server to switch protocols.

• 102 Processing: The server is currently processing the request.

• 103 Early Hints: Indicates to the client that the server is likely to send a final response with the header fields included in the informational response.

Successful Responses (200–299)

• 200 OK: The request was successful.

• 201 Created: The request has been fulfilled, and a new resource is created.

• 202 Accepted: The request has been accepted for processing, but the processing has not been completed.

• 203 Non-Authoritative Information: The server is a transforming proxy that received a 200 OK from its origin but is returning a response from a downstream server.

• 204 No Content: The server successfully processed the request but there is no content to send.

• 205 Reset Content: The server successfully processed the request, but there is no representation to return.

• 206 Partial Content: The server is delivering only part of the resource due to a range header sent by the client.

• 208 Already Reported: The members of a DAV binding have already been enumerated in a preceding part of the (multistatus) response, and are not being included again.

• 226 IM Used: The server has fulfilled a request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance.

Redirection Messages (300–399)

• 300 Multiple Choices: The requested resource has multiple choices.

• 301 Moved Permanently: The requested resource has been permanently moved to a new location.

• 302 Found: The requested resource resides temporarily under a different URI.

• 303 See Other: The response to the request can be found under a different URI.

• 304 Not Modified: The client can use cached data.

• 305 Use Proxy: Defined in a previous version of the HTTP specification to indicate that a requested response must be accessed by a proxy.

• 306 Switch Proxy: No longer used. Originally meant “Subsequent requests should use the specified proxy.”

• 307 Temporary Redirect: The requested resource resides temporarily under a different URI.

• 308 Permanent Redirect: The requested resource has been permanently moved to a different URI.

Client Error Responses (400–499)

• 400 Bad Request: The request cannot be fulfilled due to bad syntax.

• 401 Unauthorized: Similar to 403 Forbidden, but authentication is possible.

• 402 Payment Required: Reserved for future use.

• 403 Forbidden: The client does not have permission to access the requested resource.

• 404 Not Found: The requested resource could not be found.

• 405 Method Not Allowed: The method specified in the request is not allowed for the resource identified by the request URI.

• 406 Not Acceptable: The resource identified by the request is only capable of generating response entities that have content characteristics not acceptable according to the accept headers sent in the request.

• 407 Proxy Authentication Required: The client must first authenticate itself with the proxy.

• 408 Request Timeout: The server timed out waiting for the request.

• 409 Conflict: Indicates that the request could not be completed due to a conflict with the current state of the target resource.

• 410 Gone: Indicates that the resource requested is no longer available and will not be available again.

• 411 Length Required: The request did not specify the length of its content, which is required by the requested resource.

• 412 Precondition Failed: The server does not meet one of the preconditions that the requester put on the request.

• 413 Payload Too Large: The request is larger than the server is willing or able to process.

• 414 URI Too Long: The URI provided was too long for the server to process.

• 415 Unsupported Media Type: The request entity has a media type that the server or resource does not support.

• 416 Range Not Satisfiable: The client has asked for a portion of the file, but the server cannot supply that portion.

• 417 Expectation Failed: The expectation given in the request’s Expect header field could not be met by at least one of the inbound servers.

• 418 I’m a teapot: This code was defined in 1998 as one of the traditional IETF April Fools’ jokes.

• 421 Misdirected Request: The request was directed at a server that is not able to produce a response.

• 422 Unprocessable Entity: The server understands the content type of the request entity, and the syntax of the request entity is correct, but it was unable to process the contained instructions.

• 423 Locked: The source or destination resource of a method is locked.

• 424 Failed Dependency: The method could not be performed on the resource because the requested action depended on another action and that action failed.

• 425 Too Early: Indicates that the server is unwilling to risk processing a request that might be replayed.

• 426 Upgrade Required: The server refuses to perform the request using the current protocol but might be willing to do so after the client upgrades to a different protocol.

• 428 Precondition Required: The origin server requires the request to be conditional.

• 429 Too Many Requests: The user has sent too many requests in a given amount of time.

• 431 Request Header Fields Too Large: The server is unwilling to process the request because its header fields are too large.

• 451 Unavailable For Legal Reasons: A server operator has received a legal demand to deny access to a resource or to a set of resources that includes the requested resource.

Server Error Responses (500–599)

• 500 Internal Server Error: A generic error message returned when an unexpected condition was encountered.

• 501 Not Implemented: The server either does not recognize the request method or lacks the ability to fulfill the request.

• 502 Bad Gateway: The server, while acting as a gateway or proxy, received an invalid response from an inbound server.

• 503 Service Unavailable: The server is not ready to handle the request.

• 504 Gateway Timeout: The server, while acting as a gateway or proxy, did not receive a timely response from an upstream server.

• 505 HTTP Version Not Supported: The server does not support the HTTP protocol version that was used in the request.

• 506 Variant Also Negotiates: Transparent content negotiation for the request, results in a circular reference.

• 507 Insufficient Storage: The server is unable to store the representation needed to complete the request.

• 508 Loop Detected: The server detected an infinite loop while processing a request.

• 510 Not Extended: Further extensions to the request are required for the server to fulfill it.

• 511 Network Authentication Required: The client needs to authenticate to gain network access.

Unofficial HTTP Status Codes

Apache HTTP Server

• 218 This is fine: Used by Apache servers as a catch-all error condition allowing the passage of message bodies through the server when the ProxyErrorOverride setting is enabled.

Laravel Framework

• 419 Page Expired: Used by the Laravel Framework when a CSRF Token is missing or expired.

Spring Framework

• 420 Method Failure: A deprecated response status proposed during the development of WebDAV, used by the Spring Framework when a method has failed.

Twitter

• 420 Enhance Your Calm: Returned by version 1 of the Twitter Search and Trends API when the client is being rate-limited; versions 1.1 and later use the 429 Too Many Requests response code instead.

Shopify

• 430 Request Header Fields Too Large: A deprecated response used by Shopify when too many URLs are requested within a certain time frame.
• 430 Shopify Security Rejection: Used by Shopify to signal that the request was deemed malicious.
• 540 Temporarily Disabled: Used by Shopify to indicate that the requested endpoint has been temporarily disabled.
• 530 Site is frozen: Used by the Pantheon Systems web platform to indicate a site that has been frozen due to inactivity.
• 530 Origin DNS Error: Used by Shopify to indicate that Cloudflare can’t resolve the requested DNS record.
• 598 (Informal convention) Network read timeout error: Used by some HTTP proxies to signal a network read timeout error behind the proxy to a client in front of the proxy.
• 599 Network Connect Timeout Error: An error used by some HTTP proxies to signal a network connect timeout behind the proxy to a client in front of the proxy.
• 783 Unexpected Token: Used by Shopify to indicate that the request includes a JSON syntax error.

Internet Information Services (IIS)

• 440 Login Time-out: The client’s session has expired and must log in again.
• 449 Retry With: The server cannot honor the request because the user has not provided the required information.
• 451 Redirect: Used in Exchange ActiveSync when either a more efficient server is available or the server cannot access the user’s mailbox.

nginx

• 444 No Response: Used internally to instruct the server to return no information to the client and close the connection immediately.
• 494 Request header too large: Client sent too large request or too long header line.
• 495 SSL Certificate Error: An expansion of the 400 Bad Request response code, used when the client has provided an invalid client certificate.
• 496 SSL Certificate Required: An expansion of the 400 Bad Request response code, used when a client certificate is required but not provided.
• 497 HTTP Request Sent to HTTPS Port: An expansion of the 400 Bad Request response code, used when the client has made an HTTP request to a port listening for HTTPS requests.
• 499 Client Closed Request: Used when the client has closed the request before the server could send a response.

Cloudflare

• 520 Web Server Returned an Unknown Error: The origin server returned an empty, unknown, or unexpected response to Cloudflare.
• 521 Web Server Is Down: The origin server refused connections from Cloudflare. Security solutions at the origin may be blocking legitimate connections from certain Cloudflare IP addresses.
• 522 Connection Timed Out: Cloudflare timed out contacting the origin server.
• 523 Origin Is Unreachable: Cloudflare could not reach the origin server; for example, if the DNS records for the origin server are incorrect or missing.
• 524 A Timeout Occurred: Cloudflare was able to complete a TCP connection to the origin server, but did not receive a timely HTTP response.
• 525 SSL Handshake Failed: Cloudflare could not negotiate an SSL/TLS handshake with the origin server.
• 526 Invalid SSL Certificate: Cloudflare could not validate the SSL certificate on the origin web server. Also used by Cloud Foundry’s gorouter.
• 527 Railgun Error: Error 527 indicates an interrupted connection between Cloudflare and the origin server’s Railgun server.
• 530: Error 530 is returned along with a 1xxx error.

AWS Elastic Load Balancing

• 000: Returned with an HTTP/2 GOAWAY frame if the compressed length of any of the headers exceeds 8K bytes or if more than 10K requests are served through one connection.
• 460: Client closed the connection with the load balancer before the idle timeout period elapsed. Typically, when client timeout is sooner than the Elastic Load Balancer’s timeout.
• 463: The load balancer received an X-Forwarded-For request header with more than 30 IP addresses.
• 464: Incompatible protocol versions between Client and Origin server.
• 561 Unauthorized: An error around authentication returned by a server registered with a load balancer. You configured a listener rule to authenticate users, but the identity provider (IdP) returned an error code when authenticating the user.

Caching warning codes (obsoleted)

The following caching related warning codes were specified under RFC 7234. Obsoleted by RFC 9111.

• 110 Response is Stale: The response provided by a cache is stale (the content’s age exceeds a maximum age set by a Cache-Control header or heuristically chosen lifetime).
• 111 Revalidation Failed: The cache was unable to validate the response, due to an inability to reach the origin server.
• 112 Disconnected Operation: The cache is intentionally disconnected from the rest of the network.
• 113 Heuristic Expiration: The cache heuristically chose a freshness lifetime greater than 24 hours and the response’s age is greater than 24 hours.
• 199 Miscellaneous Warning: Arbitrary, non-specific warning. The warning text may be logged or presented to the user.
• 214 Transformation Applied: Added by a proxy if it applies any transformation to the representation, such as changing the content encoding, media type, or the like.
• 299 Miscellaneous Persistent Warning: Same as 199, but indicating a persistent warning.