Retry-After - HTTP 编辑

The Retry-After response HTTP header indicates how long the user agent should wait before making a follow-up request. There are three main cases this header is used:

• When sent with a 503 (Service Unavailable) response, this indicates how long the service is expected to be unavailable.
• When sent with a 429 (Too Many Requests) response, this indicates how long to wait before making a new request.
• When sent with a redirect response, such as 301 (Moved Permanently), this indicates the minimum time that the user agent is asked to wait before issuing the redirected request.

Syntax

Retry-After: <http-date>
Retry-After: <delay-seconds>

Directives

<http-date>

A date after which to retry. See the Date header for more details on the HTTP date format.

<delay-seconds>

A non-negative decimal integer indicating the seconds to delay after the response is received.

Examples

Dealing with scheduled downtime

Support for the Retry-After header on both clients and servers is still inconsistent. However, some crawlers and spiders, like the Googlebot, honor the Retry-After header. It is useful to send it along with a 503 (Service Unavailable) response, so that search engines will keep indexing your site when the downtime is over.

Retry-After: Wed, 21 Oct 2015 07:28:00 GMT
Retry-After: 120

Specifications

Browser compatibility

BCD tables only load in the browser

The compatibility table in 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

• Google Webmaster blog: How to deal with planned site downtime
• 503 (Service Unavailable)
• 301 (Moved Permanently)