Microsoft KB Archive/824847

= Some hyperlinks may fail when the server sends a VARY header response =

Article ID: 824847

Article Last Modified on 2/5/2007

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APPLIES TO


 * Microsoft Internet Explorer 6.0
 * Microsoft Internet Explorer 6.0 Service Pack 1
 * Windows Internet Explorer 7 for Windows XP
 * Windows Internet Explorer 7 for Windows Server 2003
 * Windows Internet Explorer 7 for Windows Server 2003 IA64

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SYMPTOMS
When you visit a Web site that contains a link to a file that will be opened outside Internet Explorer, and the Web site also includes the VARY header in the response to the client GET request, you may receive the following error message when you click the link and then click Open:

Error:

Cannot open the file.



CAUSE
The VARY header instructs the client not to use a cached file. Therefore, Internet Explorer does not write the .chm file to the hard disk. HTML Help requires a file. The VARY header response from the server is similar to the following: 

&quot;vary: accept-encoding, accept-language, cookie, user-agent, translate&quot;

Internet Explorer does not fully implement the VARY header per Requests for Comments (RFC) 2616. The Internet Explorer implementation of VARY is that it does not cache any data except for Vary-Useragent.



MORE INFORMATION
This problem is known to occur with HTML Help files (.chm files) and vCard files (.vcf files). Other programs that are not listed in the &quot;Applies To&quot; section of this article may also exhibit this problem. Programs that open files directly in Internet Explorer, such as Adobe Acrobat, do not exhibit this problem.

Keywords: kbprb KB824847

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