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Can't read .chm (Compiled Help) on Vista/XP/2003?

  • Article

In my previous post, I mentioned that TechNet Magazine has their past issues available in HTML Help format (.chm) here.  If you navigate to that page (with a fully patched Vista or Windows XP box) and open one of the referenced files from directly within IE, you will get something that looks a bit like the following: "The address is not valid".

The reason for this problem is addressed in the following KB article: You cannot open HTML Help files from Internet Explorer after you install security update 896358 or Windows Server 2003 Service Pack 1

SYMPTOMS

After you install security update 896358 or Microsoft Windows Server 2003 Service Pack 1 (SP1), you may experience one or both of the following symptoms after you click a link to an HTML Help .chm file in Internet Explorer:

  • Topics in the .chm file cannot be viewed when you click Open instead of Save in the File Download dialog box.
  • Topics in the .chm file cannot be viewed when you click Save in the File Download dialog box, and you then try to open the file.

CAUSE

Security update 896358 and Windows Server 2003 SP1 include changes to the InfoTech protocol that block the ability to view remote content. These changes were introduced to reduce security vulnerabilities in HTML Help. After you install 896358 or Windows Server 2003 SP1, files in the Temporary Internet Files folder are treated as content from the Internet zone. Therefore, files may be blocked when you click Open in the File Download dialog box. Additionally, after you install 896358 or Windows Server 2003 SP1, Attachment Manager may treat a downloaded .chm file as an untrusted file. Therefore, you may not be able to open the file. These effects are expected and intended effects of installing the security update and of installing Windows Server 2003 SP1.

RESOLUTION

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.

*Note: This problem (and resolution) is also covered in Chris Crowe's Blog.

Comments

  • Anonymous
    January 01, 2003
    PingBack from http://djjlewis.wordpress.com/2008/08/29/error-when-activating-sharepoint-feature-failed-to-apply-a-webconfig-modification-to-file-2/

  • Anonymous
    October 03, 2010
    thank's a lot, it really helped

  • Anonymous
    November 03, 2010
    Always look that your .chm file is not  in some folder thats named or beggining with   "  #  "  (without quotes)

  • Anonymous
    January 02, 2011
    Thnaks a lot it really helped me. Very simple yet effective solution :)

  • Anonymous
    January 22, 2011
    Thanks a lot for this, searched for this in swedish but didn't find a solution, method 2 worked for me :)

  • Anonymous
    March 08, 2011
    Thanks alot..:)

  • Anonymous
    April 17, 2011
    The comment has been removed

  • Anonymous
    April 19, 2011
    Awesome.. thanks man.. helped me at the right time..

  • Anonymous
    August 31, 2011
    Thank you.. Well-written and complete article. Method 2 solved the problem. Gracias!

  • Anonymous
    October 01, 2011
    This is simple and very effective. Thanks a lot. Spectacular job done well  :)

  • Anonymous
    November 10, 2011
    Hi i am using vista basic. i dont have the option "unblock" button, suggest me a way to open it

  • Anonymous
    February 22, 2012
    Thanks. Worked. Windows XP. Method 2

  • Anonymous
    May 14, 2012
    Thank you very much. Keep go. All the best.

  • Anonymous
    June 08, 2012
    Microsoft not much help; if their 'unblock' does not work or is missing- try the following: This worked for me in XP (not sure about Windows 7) Go to Google, search for UniExtract otherwise known as Universal Extractor ---it was free last time i looked, download, install, set to include context menus. Then right click a .chm file and the context menu choices should appear if installation was successful ---left click on extract to subdirectory, this means that the file will be extracted to a new folder same name as the .chm file. Open folder and your goodie file should be there as an htm, select the initial TOC, table of contents, left click it and it should open in your default browser, use "next" key buttons to scroll thru to your next page, so on and on.

  • Anonymous
    September 30, 2012
    thanks a lot. simple and informative :)

  • Anonymous
    April 12, 2013
    The comment has been removed

  • Anonymous
    March 15, 2015
    @Sloba - I can't thank you enough. I'm on Windows XP SP3. I'm taking a C# programming course, so my folder has C# in its name. Once I moved the file to another folder, I could open it. That's all I had to do! Thanks a lot!!!

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