Internet Explorer may not decompress HTTP content when you visit a Web site

Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows registry
BUG #: 29811 (IE OE Sustained Engineering)


When you visit a Web site, Microsoft Internet Explorer may not decompress HTTP content. You may experience this problem when all the following conditions are true:
  • Chunked encoding is enabled on the Web server.
  • HTTP compression is enabled on the Web server.
  • Data is sent from the Web server by using the HTTPS protocol.
You may experience various symptoms of this problem, depending on the content that Internet Explorer is trying to decompress. For example, if the content that is sent by the Web site server is a JavaScript file, you may receive a scripting error.


This problem occurs when a notification between WININET and URLMON is lost. When a notification is lost, an encoded chunk that is required for the decompression is lost. When an encoded chunk is lost, the gzip decompressor fails.

  • WININET (Wininet.dll) is the component that receives the HTTP data. URLMON (urlmon.dll) is the component that implements the gzip decompressor.
  • HTTP compression is also known as gzip encoding.


Service pack information

To resolve this problem, obtain the latest service pack for Windows XP. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
322389 How to obtain the latest Windows XP service pack

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. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

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, contact 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 Web site: 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.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
Microsoft Internet Explorer 6 Service Pack 1 (SP1)
   Date         Time   Version           Size  File name
14-Jan-2005 17:21 6.0.2800.1489 581,632 Wininet.dll
Microsoft Internet Explorer 6 Service Pack 2 (SP2)
   Date         Time   Version           Size  File name
10-Jun-2005 01:38 6.0.2900.2695 658,944 Wininet.dll

Installation information

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

After you install this hotfix, follow these steps:

  1. Quit Internet Explorer.
  2. Click Start, click Run, type regedit, and then click OK.
  3. Locate and then click the following registry subkey:

    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_RESET_SOCKET_FLAGS_KB871205
  4. On the Edit menu, point to New, and then click DWORD Value.

  5. Type Iexplore.exe, and then press ENTER.

  6. Right-click Iexplore.exe, and then click Modify.

  7. In the Value data box, type 00000001, and then click OK.

  8. Quit Registry Editor.


To work around this problem, disable chunked encoding or disable HTTP compression on the Web server. To view the HTTP compression settings in Microsoft Internet Information Services (IIS) 6.0, follow these steps:
  1. Click Start, point to Administrative Tools, and then click Internet Information Services (IIS) Manager.
  2. Expand the Web server, right-click Web Sites, and then click Properties.
  3. Click the Service tab, and then view the options that appear under HTTP compression.


Microsoft has confirmed that this is a problem in Microsoft Internet Explorer 6 Service Pack 1.

More Information

This problem is more likely to occur on a computer that is running Apache HTTP Server because Apache HTTP Server can use chunked encoding on any kind of file. This includes static files such as a JavaScript file or a .gif file. When the problem that is described in this article occurs, the content that is stored in the Internet Explorer cache may be truncated or corrupted.

Note By default, Microsoft Internet Information Server does not use chunked encoding. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

278998 How to enable chunked transfer encoding with IIS

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.


文書番号:871205 - 最終更新日: 2014/06/20 - リビジョン: 1