Here is a list of many common error codes:
Succesful Client Requests:
200 OK
201 Created
202 Accepted
203 Non-Authorative Information
204 No Content
205 Reset Content
206 Partial Content
Client Request Redirected:
300 Multiple Choices
301 Moved Permanently
302 Moved Temporarily
303 See Other
304 Not Modified
305 Use Proxy
Client Request Errors:
400 Bad Request
401 Authorization Required
402 Payment Required (not used yet)
403 Forbidden
404 Not Found
405 Method Not Allowed
406 Not Acceptable (encoding)
407 Proxy Authentication Required
408 Request Timed Out
409 Conflicting Request
410 Gone
411 Content Length Required
412 Precondition Failed
413 Request Entity Too Long
414 Request URI Too Long
415 Unsupported Media Type
Server Errors:
500 Internal Server Error
501 Not Implemented
502 Bad Gateway
503 Service Unavailable
504 Gateway Timeout
505 HTTP Version Not Supported
You can use these error codes to specify your own custom error pages through the .htaccess file. For example, supposing you want a custom page for anyone who experiences an internal server error, you would put this in the .htaccess file:
ErrorDocument 500 /errorpages/500error.html
This is of course assuming the file you want displayed is 500error.html located in the /errorpages director
