Abstract


2XX


201

  • Created
  • Requested resource is created successfully

204

  • No Content
  • Server successfully processed the HTTP Request, but isn’t returning any content

218

this is fine
  • This is Fine
  • Specifically for Apache servers that serve as a Reverse Proxy (反向代理) with ProxyErrorOverride on
  • For example, The Server behind Apache can send the 218 status code, so the Client will receive 218 even when there is an error code like 404

3XX


  • Redirection

301

  • Permanent Redirect
  • Telling the Client (usually a web browser or a web crawler) that the requested resource has moved permanently to a new location
  • One use case is when clients accessing via HTTP, but server only wants to serve via HTTPS

302

  • Temporary Redirect
  • The redirected page isn’t going to be indexed by search engine. The page that performs the redirects is
  • If you need to permanently move a page to a new location, we should use 301
  • Use cases are Temporary Maintenance and A/B Testing

4XX


  • Indicates the Client-side has some issues

400

  • Bad Request
  • The HTTP Request cannot be fulfilled due to bad syntax.

401

  • Unauthorised
  • You need to provide valid credentials (e.g., login information) to access this resource, and the ones you provided are not accepted

403

  • Forbidden
  • Happens when the provided Authentication information is rejected

404

  • Unfound
  • Resources can’t be found on Server

409

  • Conflict
  • Returned when the same resource is being processed
    1. Same user is created
    2. Concurrency Conflicts

418

  • I’m a teapot
  • Indicates that the Server refuses to brew coffee because it is, permanently, a teapot

420

  • Enhance Your Calm
  • Can be used to tell Client it is being rated limited for making too many requests
  • Replaced by 429

429

  • Too Many Requests
  • Returned when a request can’t be served due to rate limiting

451

  • Unavailable for legal reasons
  • Reference to Fahrenheit 451
  • The user agent requested a resource that cannot legally be provided, such as a web page censored by a government. Or like Netflix geo-lock
  • Usually can be solved with a VPN

5XX


  • Indicates the Server-side has some issues

500

  • Internal Server Error
  • Some errors on the Server

502

504

  • Gateway Timeout
  • Indicates that a Proxy, didn’t receive a timely response from an upstream server it needed to access in order to complete the request

530

  • Site Fronzen
  • Can be used when the site owner’s free trial ends, the platform freezes the public access

References


  • HTTP Status Codes that should never have been created