Export (0) Print
Expand All HTTP Error 503

One of the causes of HTTP error 503 is that more users than are allowed by the server's request queue limit have sent requests to a single server.

The error returned by the server resembles the following.

OPTIONS /Microsoft-Server-ActiveSync
Content-Type: application/vnd.ms-sync.wbxml
MS-ASProtocolVersion: 14.0

HTTP/1.1 503 Service Unavailable
Connection: close
Date: Mon, 02 Mar 2009 23:51:51 GMT
Server: Microsoft-IIS/7.0
X-Powered-By: ASP.NET
Content-Type: text/html

If a Retry-After header ([RFC2616]) is present in the response, the client SHOULD<5> retry the request after waiting the number of seconds indicated by the Retry-After header. Any such value represents an estimate of when the server is expected to be able to process the request.

If a Retry-Header is not present in the response, the client can retry the request after waiting a few seconds. The time to wait between continuous requests that result in HTTP error 503 responses can be increased exponentially to a predetermined maximum.

For more details about ASP.NET performance monitoring properties, see [MSDN-APM].

© 2015 Microsoft