CHM Error

Resolution for end users

Warning If you are prompted to open or to save a .chm file from a Web site, you should do so only if you need the file and if you trust the Web site that is providing the file.

In the File Download dialog box, click Save, and then choose where you want to save the .chm file. Then, use one of the following methods:

Method 1

1. Double-click the .chm file.
2. In the Open File-Security Warning dialog box, click to clear the Always ask before opening this file check box.
3. Click Open.

Method 2

1. Right-click the CHM file, and then click Properties.
2. Click Unblock.
3. Double-click the .chm file to open the file.

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Resolution for system administrators

To resolve this issue, use one of the following methods.

Use UNC file paths and file shares to link to .chm files

If your intranet Web page uses the HTTP URL scheme to link to .chm files, security update 896358 may prevent users from seeing topics in the .chm file. Replacing an HTTP file path with a UNC file path can make it possible again to open .chm files from the Web page.

To use a UNC file path instead of an HTTP URL, follow these steps:

1. Put the .chm files on a file share server that can be addressed by using a UNC file path.
   
   A UNC file path looks similar to the following path:
   \\productmanuals\helpfiles
2. Use the ItssRestrictions\UrlAllowList value to enable the systems in your intranet to access the .chm files from that file share.
   
   For more information, click the following article number to view the article in the Microsoft Knowledge Base:
   896054 (http://support.microsoft.com/kb/896054/ ) You cannot open remote content by using the InfoTech protocol after you install security update 896358, security update 840315, or Windows Server 2003 Service Pack 1
3. Update the links on your intranet Web page to use UNC file paths in the URLs that link to the .chm files.

Note This method works only for pages that are served from the Intranet zone. This method does not work for pages that are served from the Internet zone.

Set up Web applications to download .chm files

On the Web page that links to .chm files, add instructions that advise the user to save the file instead of opening the file directly. For more information, see the "Resolution for end users" section.

You can also use the DownloadOptions tag to remove the Open button from the File Download dialog box that appears after a user clicks a link to the .chm file. Put this tag inside the tag of your HTML page. This usage is illustrated in the following example.

For more information, visit the following Microsoft Web site:

http://msdn2.microsoft.com/library/ms534184.aspx (http://msdn2.microsoft.com/library/ms534184.aspx)

Note The use of the DownloadOptions tag is supported only in Microsoft Windows XP with Service Pack 2 and in Windows Server 2003 with Service Pack 1.