HTTP Error codes — descriptions

Browse common HTTP error codes with short descriptions.

• HTTP 400 — Bad Request
  The server could not understand the request due to invalid syntax.
• HTTP 401 — Unauthorized
  Authentication is required to access the resource.
• HTTP 402 — Payment Required
  Payment is required to access the resource.
• HTTP 403 — Forbidden
  The client does not have access rights to the content.
• HTTP 404 — Not Found
  The server can not find the requested resource.
• HTTP 405 — Method Not Allowed
  The request method is known by the server but has been disabled and cannot be used.
• HTTP 406 — Not Acceptable
  The requested content is not acceptable according to the Accept headers.
• HTTP 407 — Proxy Authentication Required
  Client must first authenticate itself with the proxy.
• HTTP 408 — Request Timeout
  Request took longer than the server was prepared to wait.
• HTTP 409 — Conflict
  Request conflicts with current state of the server.
• HTTP 410 — Gone
  The resource requested is no longer available and will not be available again.
• HTTP 411 — Length Required
  Server refuses to accept the request without a defined Content-Length.
• HTTP 412 — Precondition Failed
  Server does not meet one of the preconditions.
• HTTP 413 — Payload Too Large
  Request entity is larger than limits defined by server.
• HTTP 414 — URI Too Long
  URI requested by the client is longer than the server is willing to interpret.
• HTTP 415 — Unsupported Media Type
  Media format of the requested data is not supported.
• HTTP 416 — Range Not Satisfiable
  Range specified by the Range header can not be fulfilled.
• HTTP 417 — Expectation Failed
  The expectation indicated by the Expect header can not be met.
• HTTP 418 — I'm a teapot
  The server refuses the attempt to brew coffee with a teapot.
• HTTP 419 — Authentication Timeout
  Usually a CSRF authentication timeout (non-standard).
• HTTP 421 — Misdirected Request
  Request was directed to a server that is not able to produce a response.
• HTTP 422 — Unprocessable Entity
  The request was well-formed but was unable to be followed due to semantic errors.
• HTTP 423 — Locked
  The resource is locked.
• HTTP 424 — Failed Dependency
  The request failed due to failure of a previous request.
• HTTP 425 — Too Early
  Indicates that the server is unwilling to risk processing a request that might be replayed.
• HTTP 426 — Upgrade Required
  Client should switch to a different protocol.
• HTTP 428 — Precondition Required
  The origin server requires the request to be conditional.
• HTTP 429 — Too Many Requests
  The user has sent too many requests in a given amount of time.
• HTTP 431 — Request Header Fields Too Large
  Request header fields are too large.
• HTTP 449 — Retry With
  Retry With (non-standard).
• HTTP 451 — Unavailable For Legal Reasons
  The user-agent requested a resource that cannot legally be provided.
• HTTP 499 — Client Closed Request (Nginx)
  Client closed request (Nginx extension) — the client closed the connection before the server responded.
• HTTP 500 — Internal Server Error
  The server encountered an unexpected condition.
• HTTP 501 — Not Implemented
  The server does not support the functionality required to fulfill the request.
• HTTP 502 — Bad Gateway
  The server received an invalid response from the upstream server.
• HTTP 503 — Service Unavailable
  The server is not ready to handle the request.
• HTTP 504 — Gateway Timeout
  The server is acting as a gateway and cannot get a response in time.
• HTTP 505 — HTTP Version Not Supported
  The HTTP version used is not supported.
• HTTP 506 — Variant Also Negotiates
  Transparent content negotiation for the request results in a circular reference.
• HTTP 507 — Insufficient Storage
  The server is unable to store the representation needed to complete the request.
• HTTP 508 — Loop Detected
  A loop was detected while processing the request.
• HTTP 509 — Bandwidth Limit Exceeded
  Bandwidth limit exceeded.
• HTTP 510 — Not Extended
  Further extensions to the request are required for the server to fulfill it.
• HTTP 511 — Network Authentication Required
  The client needs to authenticate to gain network access.
• HTTP 520 — Unknown Error
  Unknown error (Cloudflare).
• HTTP 521 — Web Server Is Down
  Web server is down (Cloudflare).
• HTTP 522 — Connection Timed Out
  Connection timed out (Cloudflare).
• HTTP 523 — Origin Is Unreachable
  Origin is unreachable (Cloudflare).
• HTTP 524 — A Timeout Occurred
  A timeout occurred (Cloudflare).
• HTTP 525 — SSL Handshake Failed
  SSL handshake failed (Cloudflare).
• HTTP 526 — Invalid SSL Certificate
  Invalid SSL certificate (Cloudflare).

HTTP error pages: 4xx/5xx status codes — descriptions and test pages

Browse and test common HTTP errors such as 400, 404, 500, 502, 503. These server-rendered pages return real HTTP status codes so you can validate monitoring, alerts, proxies and CDNs.

Use the /errors directory as a reference with short explanations for each status code, links to related codes and localized content for multiple languages.