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Vary header is overwritten as "Accept-Encoding" after you enable dynamic content compression in Windows


View products that this article applies to.

Symptoms

When you enable dynamic content compression on a computer that is running Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7 Service Pack 1 (SP1), or Windows Server 2008 R2 SP1, a Vary header is overwritten as "Accept-Encoding."

For example, in an .aspx page, you set the Vary header as "User-Agent" by using the following code:
using System; 
using System.Collections.Generic;
using System.Web;
using System.Web.UI;

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

Response.Write("Hello");
Response.AppendHeader("Vary", "User-Agent");

}
}
If dynamic content compression is not enabled, the output information resembles the following:
HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Vary: User-Agent
Server: Microsoft-IIS/7.5
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Fri, 07 Dec 2012 03:17:29 GMT
Content-Length: 584

However, if dynamic content compression is enabled, the Vary header is overwritten as "Accept-Encoding," and the output information resembles the following:
HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Content-Encoding: gzip
Vary: Accept-Encoding
Server: Microsoft-IIS/7.5
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Fri, 07 Dec 2012 03:18:33 GMT
Content-Length: 572

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Resolution

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website: Note The "Hotfix Download Available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must be running one of the following operating systems:
  • Windows 8.1
  • Windows Server 2012 R2
  • Windows 8
  • Windows Server 2012
  • Windows 7 SP1
  • Windows Server 2008 R2 SP1
For more information about how to obtain a Windows 7 or Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.
File information
The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.


Windows 8.1 and Windows Server 2012 R2 file information notes
Important Windows 8.1 hotfixes and Windows Server 2012 R2 hotfixes are included in the same packages. However, only "Windows 8.1" is listed on the Hotfix Request page. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 8.1" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:

    VersionProductMilestoneService branch
    6.3.960 0.16 xxxWindows 8.1 and Windows Server 2012 R2RTMGDR
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows 8.1 and Windows Server 2012 R2" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
For all supported x86-based versions of Windows 8.1
File nameFile versionFile sizeDateTimePlatform
Compdyn.dll8.5.9600.1645730,20808-Nov-201304:26x86
For all supported x64-based versions of Windows 8.1 and of Windows Server 2012 R2
File nameFile versionFile sizeDateTimePlatform
Compdyn.dll8.5.9600.1645742,49608-Nov-201305:00x64
Compdyn.dll8.5.9600.1645730,20808-Nov-201304:26x86
Windows 8 and Windows Server 2012 file information notes
Important Windows 8 hotfixes and Windows Server 2012 hotfixes are included in the same packages. However, only "Windows 8" is listed on the Hotfix Request page. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 8" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:

    VersionProductMilestoneService branch
    6.2.920 0.20 xxxWindows 8 and Windows Server 2012RTMLDR
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows 8 and Windows Server 2012" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
For all supported x86-based versions of Windows 8
File nameFile versionFile sizeDateTimePlatform
Compdyn.dll8.0.9200.2086929,18404-Nov-201323:32x86
For all supported x64-based versions of Windows 8 and of Windows Server 2012
File nameFile versionFile sizeDateTimePlatform
Compdyn.dll8.0.9200.2086943,00804-Nov-201323:35x64
Compdyn.dll8.0.9200.2086929,18404-Nov-201323:32x86
Windows 7 and Windows Server 2008 R2 file information notes
Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
  • The files that apply to a specific product, SR_Level (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    VersionProductMilestoneService branch
    6.1.760
    1.22xxx
    Windows 7 and Windows Server 2008 R2SP1LDR
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows 7 and for Windows Server 2008 R2" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintaining the state of the updated component. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
For all supported x86-based versions of Windows 7
File nameFile versionFile sizeDateTimePlatform
Compdyn.dll7.5.7601.2250242,49605-Nov-201309:26x86
For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Compdyn.dll7.5.7601.2250246,08005-Nov-201310:47x64
Compdyn.dll7.5.7601.2250242,49605-Nov-201309:26x86
For all supported IA-64-based versions of Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Compdyn.dll7.5.7601.2250289,60005-Nov-201309:45IA-64
Compdyn.dll7.5.7601.2250242,49605-Nov-201309:26x86


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Workaround

To work around the issue, write two HTTP modules to listen on the RQ_SEND_RESPONSE event notification to add back the original Vary header value. One HTTP module is used to store the original Vary header value before the compression, and the other HTTP module is used to restore the Vary header value after the compression.

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Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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More Information

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates
Additional file information

Additional file information for Windows 8.1 and Windows Server 2012 R2

Additional files for all supported x86-based versions of Windows 8.1
File propertyValue
File nameX86_67e665de430797e566b34074602255b9_31bf3856ad364e35_6.3.9600.16457_none_817c65c742e97645.manifest
File versionNot applicable
File size722
Date (UTC)08-Nov-2013
Time (UTC)20:16
File nameX86_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.3.9600.16457_none_1cd3de6c4b42c0c9.manifest
File versionNot applicable
File size3,065
Date (UTC)08-Nov-2013
Time (UTC)08:42
Additional files for all supported x64-based versions of Windows 8.1 and of Windows Server 2012 R2
File propertyValue
File nameAmd64_0ca9258cb95c7a69c528da655645a3bf_31bf3856ad364e35_6.3.9600.16457_none_aa7c672a8e052e6b.manifest
File versionNot applicable
File size1,094
Date (UTC)08-Nov-2013
Time (UTC)20:16
File nameAmd64_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.3.9600.16457_none_78f279f003a031ff.manifest
File versionNot applicable
File size3,071
Date (UTC)08-Nov-2013
Time (UTC)10:25
File nameWow64_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.3.9600.16457_none_834724423800f3fa.manifest
File versionNot applicable
File size3,071
Date (UTC)08-Nov-2013
Time (UTC)08:40

Additional file information for Windows 8 and Windows Server 2012

Additional files for all supported x86-based versions of Windows 8
File propertyValue
File nameX86_dfdf42e825e8ebea29f5c8dcd62c3032_31bf3856ad364e35_6.2.9200.20869_none_d33717971ef9d0d2.manifest
File versionNot applicable
File size722
Date (UTC)05-Nov-2013
Time (UTC)20:32
File nameX86_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.2.9200.20869_none_855ff8eb1a33d62a.manifest
File versionNot applicable
File size3,065
Date (UTC)05-Nov-2013
Time (UTC)00:08
Additional files for all supported x64-based versions of Windows 8 and of Windows Server 2012
File propertyValue
File nameAmd64_ddba2377cd28a9a557124c3b98ea1749_31bf3856ad364e35_6.2.9200.20869_none_17199fe1b4059dbb.manifest
File versionNot applicable
File size1,094
Date (UTC)05-Nov-2013
Time (UTC)20:35
File nameAmd64_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.2.9200.20869_none_e17e946ed2914760.manifest
File versionNot applicable
File size3,071
Date (UTC)05-Nov-2013
Time (UTC)02:53
File nameWow64_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.2.9200.20869_none_ebd33ec106f2095b.manifest
File versionNot applicable
File size3,071
Date (UTC)04-Nov-2013
Time (UTC)23:53

Additional file information for Windows 7 and for Windows Server 2008 R2

Additional files for all supported x86-based versions of Windows 7
File propertyValue
File nameX86_043ce6947c70b1bbf49e07650c6f34b3_31bf3856ad364e35_6.1.7601.22502_none_165a2ac799bbbfc0.manifest
File versionNot applicable
File size722
Date (UTC)05-Nov-2013
Time (UTC)21:37
File nameX86_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.1.7601.22502_none_8aaa64bda71dbce2.manifest
File versionNot applicable
File size3,369
Date (UTC)05-Nov-2013
Time (UTC)10:41
Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
File propertyValue
File nameAmd64_4d649c0e269c7f9981d93b8405047df9_31bf3856ad364e35_6.1.7601.22502_none_ac410899baedf697.manifest
File versionNot applicable
File size1,094
Date (UTC)05-Nov-2013
Time (UTC)21:37
File nameAmd64_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.1.7601.22502_none_e6c900415f7b2e18.manifest
File versionNot applicable
File size3,375
Date (UTC)05-Nov-2013
Time (UTC)11:19
File nameWow64_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.1.7601.22502_none_f11daa9393dbf013.manifest
File versionNot applicable
File size3,032
Date (UTC)05-Nov-2013
Time (UTC)10:08
Additional files for all supported IA-64-based versions of Windows Server 2008 R2
File propertyValue
File nameIa64_fcb8e1a061ef3157c77af37aed6898b2_31bf3856ad364e35_6.1.7601.22502_none_04cd0e8ffd12b0da.manifest
File versionNot applicable
File size1,092
Date (UTC)05-Nov-2013
Time (UTC)21:37
File nameIa64_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.1.7601.22502_none_8aac08b3a71bc5de.manifest
File versionNot applicable
File size3,372
Date (UTC)05-Nov-2013
Time (UTC)10:24
File nameWow64_microsoft-windows-i..siondynamicbinaries_31bf3856ad364e35_6.1.7601.22502_none_f11daa9393dbf013.manifest
File versionNot applicable
File size3,032
Date (UTC)05-Nov-2013
Time (UTC)10:08

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Keywords: kb, kbautohotfix, kbqfe, kbhotfixserver, kbfix, kbsurveynew, kbexpertiseadvanced

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Article Info
Article ID : 2877816
Revision : 3
Created on : 4/17/2018
Published on : 4/18/2018
Exists online : False
Views : 387