The following represent issues concerning the use of HTML Help Files (.CHM help files).

Note that 2BrightSparks provides a fully searchable on-line version of the common SyncBack help file which can be accessed here: 

In common with all recent versions of our Help file, this covers SyncBackFree/SE/Pro all-in-one: see the opening remarks in the 'Welcome to the SyncBack Product Line' section for more background.

CHM Help Files without right pane content

The help file opens with all topics in the tree on the left, but a "Page Not found" error appears in the right area.

The CHM file opened since the topic list is there, but the help file (which uses Internet Explorer) refuses to display the content.

This is not a problem with the help file itself but a problem with Internet Explorer and the security settings. The issue is that the CHM engine is essentially driven through Internet Explorer via an ActiveX control that handles the display and custom manipulation that provides the CHM HTML view behaviors. The problem is the ActiveX control as it relates to the security zone/settings. These may be IE, Firewall, or Network settings which may require changes.

Problems opening CHM Help Files over a network

When a CHM file is opened from a UNC path or from a network drive, even if the network drive is mapped to a drive letter, the HTML Help viewer opens and instead of displaying the topic, it displays an error message "Action cancelled" in the topic pane.

Microsoft released a security fix on 9 September 2005 called "MS05-026: A vulnerability in HTML Help could allow remote code execution". The "fix" prevents CHM help files being viewed over a network.


How to fix the CHM file over a network problem

(1) Install the CHM files locally: When the program is distributed, install the accompanying CHM files on the local drive (perhaps install them in the WindowsHelp folder).

If this is not possible (and that’s the case for programs already distributed), the user must re-enable the execution of HTML Help files for the "Local Intranet Zone". This solution is described in the Microsoft knowledge base article linked to above. Here is a summary:

(2) Re-enable the execution of HTML Help files: Open the Windows registry and go to the key code 


Set the value of MaxAllowedZone to 1.

Go to the key code:


and also set the value of MaxAllowedZone to 1.

“MaxAllowedZone”=dword:00000001 means that access is granted to the local zone (local hard drive) and the local intranet zone (network).

This step must be performed on every client computer in the organization to enable HTML Help.