Friday, October 30, 2009

Navigation to the webpage was canceled

For many years, SQL Anywhere has used Microsoft Compiled HTML Help files (*.chm) to deliver all the manuals in one easy-to-read, easy-to-search package on your desktop, one that doesn't make you wander through endless menus and wait for slow-loading web pages.

These files are easy to copy, too, and sometimes folks copy the Help files from machine to machine without using the official SQL Anywhere setup.exe... and they zip them up and send them by email as well.

Suddenly, however, that process has become fraught with error: On the receiving end, when you open the *.chm file, you get "Navigation to the webpage was canceled" no matter which topic you navigate to:

Steven McDowell has the answer (and by the way, the problem DOES NOT AFFECT files installed by the official setup):

from Steven McDowell
to Breck Carter
date Wed, Oct 28, 2009 at 5:11 PM
subject Files downloaded from our FTP site can be "blocked" on XP/Vista/Win 7

Hi Breck,

FYI ... my investigation of your "blocked" CHMs seems to have determined what is going on.


It appears that a recent Windows security update may have further restricted the use of CHM files on XP and Vista. I don't know if other file types are affected by this, but I thought I would share the info since we often ZIP files and send them via FTP to customers and other staff.

Sneak peak: It actually appears to be an IE "feature". That's all you get here. See conclusion at bottom. :-)

It was reported that our CHM docs failed to open on an XP computer. The CHMs had been zipped here and copied via FTP. When they were unzipped, they were marked as "blocked" and the contents could not be viewed until each file was unblocked.

I have reproduced the problem on my Windows 7 system. I am an administrator but still have UAC turned on. Here is what I encountered:
* Unzipping to a local temp folder proceeds normally.
* When I try to open one of the CHMs, I get:
* If I leave the "Always ask" checkbox checked and click Open, the CHM opens, but the contents pane is blocked (with an unhelpful message). This behaviour is the same as trying to open a CHM from a network drive, but this is happening on a local drive.

* As long as the "Always ask" checkbox is checked, the contents pane is blocked for that file regardless of how many times you try to open it. Once I uncheck the box and click Open, not one but two things happen: 1) the contents pane is visible, and, 2) the dialog no longer appears. So something in the file's attributes has changed permanently.

* I picked another CHM file that had not been opened yet. I displayed its Properties. Note the Unblock button and the text to the left. This button and text are not displayed in the Properties for CHMs that were opened with the checkbox turned off. So, the "Always ask" checkbox has the dual purpose of suppressing the dialog and marking the file as unblocked.

Fortunately, it appears that using our doc install does not trigger this blocking problem. There is the possibility that other file types sent via ZIP (and probably other file copy methods) will also encounter these issues.

I did find one discussion (in the link below) that suggests it is IE that is noting that the files came from "the Internet" and marking them as blocked. I'm not sure how that works inside a ZIP file, but it appears to. Possibly non-IE transfers will not do this. CONFIRMED! I downloaded the same ZIP file via FTP using Firefox instead of IE and the files are not blocked!

Relevant URLs (Google "windows chm file blocked"):


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