HTTP status codes

This chapter aims to list all HTTP status codes that Cowboy may return, with details on the reasons why. The list given here only includes the replies that Cowboy sends, not user replies.

100 Continue

When the client sends an expect: 100-continue header, Cowboy automatically sends a this status code before trying to read the request body. This behavior can be disabled using the appropriate body option.

101 Switching Protocols

This is the status code sent when switching to the Websocket protocol.

200 OK

This status code is sent by cowboy_rest.

201 Created

This status code is sent by cowboy_rest.

202 Accepted

This status code is sent by cowboy_rest.

204 No Content

This status code is sent when the processing of a request ends without any reply having been sent. It may also be sent by cowboy_rest under normal conditions.

300 Multiple Choices

This status code is sent by cowboy_rest.

301 Moved Permanently

This status code is sent by cowboy_rest.

303 See Other

This status code is sent by cowboy_rest.

304 Not Modified

This status code is sent by cowboy_rest.

307 Temporary Redirect

This status code is sent by cowboy_rest.

400 Bad Request

Cowboy will send this status code for any of the following reasons:

Too many empty lines were sent before the request.
The request-line could not be parsed.
Too many headers were sent.
A header name was too long.
A header value was too long.
The host header was missing from an HTTP/1.1 request.
The host header could not be parsed.
The requested host was not found.
The requested path could not be parsed.
The accept header could not be parsed when using REST.
REST under normal conditions.
A Websocket upgrade failed.

401 Unauthorized

This status code is sent by cowboy_rest.

403 Forbidden

This status code is sent by cowboy_rest.

404 Not Found

This status code is sent when the router successfully resolved the host but didn't find a matching path for the request. It may also be sent by cowboy_rest under normal conditions.

405 Method Not Allowed

This status code is sent by cowboy_rest.

406 Not Acceptable

This status code is sent by cowboy_rest.

408 Request Timeout

Cowboy will send this status code to the client if the client started to send a request, indicated by the request-line being received fully, but failed to send all headers in a reasonable time.

409 Conflict

This status code is sent by cowboy_rest.

410 Gone

This status code is sent by cowboy_rest.

412 Precondition Failed

This status code is sent by cowboy_rest.

413 Request Entity Too Large

This status code is sent by cowboy_rest.

414 Request-URI Too Long

Cowboy will send this status code to the client if the request-line is too long. It may also be sent by cowboy_rest under normal conditions.

415 Unsupported Media Type

This status code is sent by cowboy_rest.

500 Internal Server Error

This status code is sent when a crash occurs in HTTP, loop or REST handlers, or when an invalid return value is returned. It may also be sent by cowboy_rest under normal conditions.

501 Not Implemented

This status code is sent by cowboy_rest.

503 Service Unavailable

This status code is sent by cowboy_rest.

505 HTTP Version Not Supported

Cowboy only supports the versions 1.0 and 1.1 of HTTP. In all other cases this status code is sent back to the client and the connection is closed.