How To Fix .CHM Files Not Opening Properly Problem On Windows 7 And Windows Vista

So you downloaded a help documentation from internet that is in .CHM format and trying hard to open it in your Windows 7 or Windows Vista PC. Help documentations downloaded from internet are usually in .CHM (Compiled HTML Help) format.

When you open such files, you end up with “Navigation to the webpage was canceled”or “Action Canceled” error message. The reason behind this issue is due to security protection in Windows 7 and Windows Vista.

Windows blocks the display of the content downloaded from the Internet. Check the screen shot below in which we were unable to read the content of the CHM file.

Navigation-canceled-chm-file If you are sure that the downloaded help documentation from internet is from a trusted source, go ahead and open it by following the below steps:

1. Right-click on the download CHM file and click “Properties”.


2. In the General tab of the properties dialog box, click “Unblock” button. You can see the security reason mentioned there… “This file came from another computer and might be blocked to help protect this computer”.


3. Click “OK”.

Now try opening the download CHM file. It should open with all the contents. Our test CHM file now opened with all the contents in the screenshot below.


Kiran Kumar

Hi there! Kiran Kumar is an Engineer by profession, and loves blogging primarily on Microsoft Windows operating system and also enjoys reviewing software and products. Currently, he is exploring Windows 10 and you will see a lot of articles on know-how about it. When he is not writing for TWP, he enjoys time with his Family, listens to lot of music, enjoys Biking, and occasionally plays racing games on Xbox One.

  • MasIs

    It works.
    Thax alot guys.
    No need to install any MS applications which in turn might brings about little problems of certificate issues.

  • Dennis George

    Thanx guys !!!! .. it has solved my problem …

  • Hapus

    I’m trying to open a “.chm” file that I received from a software developer.
    I can’t open the file. The developer says to open the properties window and
    click on the “Unblock” button. I don’t have an “unblock” button. I’m
    running Windows XP Pro, SP2.