Warning - HTTP 编辑

Note: The Warning header is soon to be deprecated; see Warning (https://github.com/httpwg/http-core/issues/139) and Warning: header & stale-while-revalidate (https://github.com/whatwg/fetch/issues/913) for more details.

The Warning general HTTP header contains information about possible problems with the status of the message. More than one Warning header may appear in a response.

Warning header fields can in general be applied to any message, however some warn-codes are specific to caches and can only be applied to response messages.

Syntax

Warning: <warn-code> <warn-agent> <warn-text> [<warn-date>]

Directives

<warn-code>

A three-digit warning number. The first digit indicates whether the Warning is required to be deleted from a stored response after validation.

• 1xx warn-codes describe the freshness or validation status of the response and will be deleted by a cache after deletion.

• 2xx warn-codes describe some aspect of the representation that is not rectified by a validation and won't be deleted by a cache after validation unless a full response is sent.

<warn-agent>

The name or pseudonym of the server or software adding the Warning header (might be "-" when the agent is unknown).

<warn-text>

Advisory text describing the error.

<warn-date>

Optional. If more than one Warning header is sent, include a date that matches the Date header.

Warning codes

The HTTP Warn Codes registry at iana.org defines the namespace for warn codes.

Examples

Warning: 110 anderson/1.3.37 "Response is stale"

Date: Wed, 21 Oct 2015 07:28:00 GMT
Warning: 112 - "cache down" "Wed, 21 Oct 2015 07:28:00 GMT"

Specifications

Browser compatibility

BCD tables only load in the browser

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

See also

• Date
• HTTP response status codes