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:
503
(Service Unavailable) response, this indicates how long the service is expected to be unavailable.429
(Too Many Requests) response, this indicates how long to wait before making a new request.301
(Moved Permanently), this indicates the minimum time that the user agent is asked to wait before issuing the redirected request.Header type | Response header |
---|---|
Forbidden header name | no |
Retry-After: <http-date> Retry-After: <delay-seconds>
Date
header for more details on the HTTP date format.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
Specification | Title |
---|---|
RFC 7231, section 7.1.3: Retry-After | Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content |
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | ? | Yes | No1 | ? | ? | ? |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
Basic support | ? | ? | Yes | ? | ? | ? | ? |
1. See Bug 230260.
503
(Service Unavailable)301
(Moved Permanently)
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https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Retry-After