HTTP Web Server Status Codes and Messages

Informational

HTTP Error 100  – Continue
HTTP Error 101 – Switching Protocols
HTTP Error 102 – Processing

Successful

HTTP Error 200 – OK
HTTP Error 201 – Created
HTTP Error 202 – Accepted
HTTP Error 203 – Non-Authoritative Information
HTTP Error 204 – No Content
HTTP Error 205 – Reset Content
HTTP Error 206 – Partial Content

Redirection

HTTP Error 300 – Multiple Choices
HTTP Error 301 – Moved Permanently
HTTP Error 302 – Found (default in mod_rewrite)
HTTP Error 303 – See Other
HTTP Error 304 – Not Modified
HTTP Error 305 – Use Proxy
HTTP Error 306 – Switch Proxy
HTTP Error 307 – Temporary Redirect

Client Error

HTTP Error 400 – Bad Request
HTTP Error 401 – Unauthorized
HTTP Error 402 – Payment Required
HTTP Error 403 – Forbidden
HTTP Error 404 – Not Found
HTTP Error 405 – Method Not Allowed
HTTP Error 406 – Not Acceptable
HTTP Error 407 – Proxy Authentication Required
HTTP Error 408 – Request timeout
HTTP Error 409 – Conflict
HTTP Error 410 – Gone
HTTP Error 411 – Length Required
HTTP Error 412 – Precondition Failed
HTTP Error 413 – Request Entity Too Large
HTTP Error 414 – Request-URI Too Long
HTTP Error 415 – Unsupported Media Type
HTTP Error 416 – Requested Range Not Satisfiable
HTTP Error 417 – Expectation Failed

Server Error

HTTP Error 500 – Internal Server Error
HTTP Error 501 – Not Implemented
HTTP Error 502 – Bad Gateway
HTTP Error 503 – Service Unavailable
HTTP Error 504 – Gateway Timeout
HTTP Error 505 – HTTP Version Not Supported

The above HTTP Status Codes are bifurcated in to five different classes:

Class 1 – HTTP Status Codes 100:
The http status messages field 100 is for provisional replies to either inform the sending multipart messages, or change the protocol.

Class 2 – HTTP Status Codes 200:
These codes are to notify the client that his requests are received correctly, understood or was accepted.

Class 3 – HTTP Status Codes 300:
These status codes indicates the forwarding (ie. redirects).

Class 4 – HTTP Status Codes 400:
These http status codes are “Error” messages. A well-known status code known among them is 404 Not Found. If a search engine crawler found this error, one can assume that the URL has been removed from the dataset.

Class 5 – HTTP Status Codes 500:
These http status codes includes server error messages. If a search engine crawler found these class 5 codes, usually the crawler will come at a later date.