Article ID: 947230 - Last Review: January 28, 2008 - Revision: 1.1

After a Windows Vista-based computer sends a POST request to a Web server, the same request is resent

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SYMPTOMS

After a Windows Vista-based computer uses a Windows HTTP Services (WinHTTP) component, such as the ServerXmlHttp object, to send a POST request to a Web server, the same request is resent to the server.

This behavior occurs if the keep-alive connection that is used for the first POST request is reset by the Web server.

Note To verify this behavior, you can use a network sniffer, or you can check the WinHTTP log.

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CAUSE

WinHTTP does not distinguish between a direct connection and a connection that uses a proxy server. For more information, see the "8.2.4 Client Behavior if Server Prematurely Closes Connection" section of Request for Comments (RFC) 2616, "Hypertext Transfer Protocol -- HTTP/1.1." To do this, visit the following Internet Engineering Task Force (IETF) Web site:

http://www.rfc-editor.org/ (http://www.rfc-editor.org/)

WinHTTP assumes that the server did not receive the POST request when it detects that the connection has been reset on the Web server. And then, WinHTTP resends the complete POST request.

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STATUS

This behavior is by design.

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MORE INFORMATION

Unlike Internet Explorer, WinHTTP does not have a feature key mechanism for WinHTTP-related applications. Therefore, adding a registry entry to change this behavior in WinHTTP may cause unintended application compatibility issues on other WinHTTP-based clients.

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