Before going into the detailed description of each status codes we need to understand some definitions which are necessary to fully understand the terms used in this context.
What is Hypertext Transfer Protocol (HTTP)?
HTTP is a stateless protocol means (the request which client generated must have some response from server and no data reside on server while processing both). Http Follow client-server approach as client send request from browser and in return server response. For every request you send to server you have to wait for response that browser shows in the form or HTML.
HTTP consist of Headers, Cookies, DNS Prefetching, Response Codes, Request Methods and Access Authentication.
We Will discuss in detail about the main backbones of HTTP Request-Response Model.
There are several versions of HTTP, but currently HTTP 1.1 is in use.
Hope you understand the basics of HTTP, Now Let's start with the key area of HTTP Request - Response Model which is Http Response Codes.
HTTP Response Codes
These provide information about certain HTTP Requests either they are completed or not.
These are 3 digit codes.
These are grouped in to five major categories enlisted below:
| Status Code Group | Status Info | Status Description |
| 1xx | Informational | Continue and processing. |
| 2xx | Success | Response Successful, no action required, Ok Status |
| 3xx | Redirection | Need more action to fulfill the request. |
| 4xx | Client Error | The Request contains unknown syntax and server did not fulfill the request. |
| 5xx | Server Error | The Server failed to fulfill the valid request. |
List of Common HTTP Status Response Codes
- 200 OK
- 300 Multiple Choices
- 301 Moved Permanently
- 302 Found
- 304 Not Modified
- 307 Temporary Redirect
- 400 Bad Request
- 401 Unauthorized
- 403 Forbidden
- 404 Not Found
- 410 Gone
- 500 Internal Server Error
- 501 Not Implemented
- 503 Service Unavailable
- 550 Permission denied
Code and Description of Other Response Codes
1xx Informational Responses
HTTP status codes in the 1xx are typically informational.
- 100 Continue
- 101 Switching Protocols
- 102 Processing
- 103 Checkpoint
- 122 Request-URI too long
2xx Successful Responses
Status codes in the 2xx range indicate that the transaction was received, understood, accepted and processed successfully.
- 200 OK
- 201 Created
- 202 Accepted
- 203 Non-Authoritative Information (since HTTP/1.1)
- 204 No Content
- 205 Reset Content
- 206 Partial Content
- 207 Multi-Status (WebDAV) (RFC 4918)
- 226 IM Used (RFC 3229)
3xx Redirection Responses
HTTP status codes in the 3xx range pertain to redirection. The client must take additional action to complete the request.
- 300 Multiple Choices
- 301 Moved Permanently
- 302 Found
- 303 See Other (since HTTP/1.1)
- 304 Not Modified
- 305 Use Proxy (since HTTP/1.1)
- 306 Switch Proxy
- 307 Temporary Redirect (since HTTP/1.1)
- 308 Resume Incomplete
4xx Client Error
HTTP status codes in the 4xx range indicate that a problem occurred with the request.
- 400 Bad Request
- 401 Unauthorized
- 402 Payment Required
- 403 Forbidden
- 404 Not Found
- 405 Method Not Allowed
- 406 Not Acceptable
- 407 Proxy Authentication Required
- 408 Request Timeout
- 409 Conflict
- 410 Gone
- 411 Length Required
- 412 Precondition Failed
- 413 Request Entity Too Large
- 414 Request-URI Too Long
- 415 Unsupported Media Type
- 416 Requested Range Not Satisfiable
- 417 Expectation Failed
- 418 I'm a teapot (RFC 2324)
- 422 Unprocessable Entity (WebDAV) (RFC 4918)
- 423 Locked (WebDAV) (RFC 4918)
- 424 Failed Dependency (WebDAV) (RFC 4918)
- 425 Unordered Collection (RFC 3648)
- 426 Upgrade Required (RFC 2817)
- 428 Precondition Required
- 429 Too Many Requests
- 431 Request Header Fields Too Large
- 444 No Response
- 449 Retry With
- 450 Blocked by Windows Parental Controls
- 499 Client Closed Request
5xx Server Error
Error codes in the 5xx range indicate that server is aware that it has encountered an error or is otherwise incapable of performing the request.
- 500 Internal Server Error
- 501 Not Implemented
- 502 Bad Gateway
- 503 Service Unavailable
- 504 Gateway Timeout
- 505 HTTP Version Not Supported
- 506 Variant Also Negotiates (RFC 2295)
- 507 Insufficient Storage (WebDAV) (RFC 4918)
- 509 Bandwidth Limit Exceeded (Apache bw/limited extension)
- 510 Not Extended (RFC 2774)
- 511 Network Authentication Required
- 598 (Informal convention) network read timeout error
- 599 (Informal convention) network connect timeout error
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