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Why does my CHM have a blank content pane?

This is a relatively old problem now, but one that keeps popping up.

You open a CHM but you don’t see your content in the right-hand pane of the HH window. You see a cryptic browser message “Navigation to the webpage was canceled” or “Action canceled”.

image5.jpg

This is due again to Microsoft plugging security holes in Windows. I’ve listed all the HH security fix problems here.  This particular problem is either:

  1. CHMs no longer work on the Intranet or Internet
    This can be fixed by a simple registry tweak (see link)
  2. Downloaded CHMs cannot be opened
    After downloading, right-click the chm file, select properties, then click “Unblock”.

hhsec2.jpg

This entry was posted on Friday, April 20th, 2007 at 11:08 am and is filed under MS HTML Help 1.x, MS Help. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

40 Responses to “Why does my CHM have a blank content pane?”

  1. rethus says:
    April 20, 2007 at 7:08 pm

    Thank you for the fast reaction to my question. Meant that, each user – who wants to read the CHM-File – must do this Registry-Patch, or must only the System be patches, where the CHM-File is created?

    Reply
  2. Rob says:
    April 20, 2007 at 7:50 pm

    Its done in the client PC registry, _not_ on the server.

    Reply
  3. Ian says:
    March 12, 2008 at 2:30 am

    Superb post. Many thanks… saved me from a major headache :)

    Reply
  4. praveen Vijayan says:
    August 16, 2008 at 6:09 pm

    Thanks dude..

    nice post

    Reply
  5. JJJ says:
    August 21, 2008 at 10:46 am

    Sweet! Thanks for the quick fix!

    Reply
  6. M J says:
    August 26, 2008 at 8:50 am

    Huge help thanks, I never knew about the “unblock” button.

    Reply
  7. Willi says:
    September 22, 2008 at 8:06 pm

    Maybe I am offtopic, maybe it is somehow linked to this…

    the content pane works fine, but for a lot of .CHM files when I click on “Index” i get (on the left side) an empty keword selection – also search remains just empty. The PS has Windows XP with all SP and automatic updates installed.

    The funny thing is, that on another PC everything the same files just work fine. The index is displayed, search is working fine…

    Any suggestions?

    Kind regards,
    Willi

    Reply
  8. Rob says:
    October 6, 2008 at 8:48 am

    Hi Willi
    HH Runtime can become unstable on a PC for 2 reasons that I know of.
    1. You installed naughty authoring software that installed Microsoft Help DLLs. MS Help DLLs are part of the OS and should never be updated in this way. A mismatch of DLLs can screw help and produce effects like you are seeing.
    2. Windows update can skip HH Dlls. These DLLs need to be updated using a separate KB install package.

    Run MJs Diags on both systems (good and bad one) and compare the outout logs. http://helpware.net/downloads/#MJs

    Check the MJs Diags logs. Make sure the DLL paths are the same (if different you may have installed bad software). Make sure the DLL versions are the same (you may need to update your system).

    More reading
    http://helpware.net/htmlhelp/hh_diags.htm
    Cheers
    Rob

    Reply
  9. Constantin says:
    October 29, 2008 at 4:03 pm

    Very concise and helpful post. Thanks a lot. Saved my time.

    Reply
  10. Tamil Maalai says:
    November 30, 2008 at 4:11 pm

    Thanks a lot… saved my time…

    Reply
  11. thelONE says:
    December 13, 2008 at 10:04 pm

    Very helpful….

    Reply
  12. veryGr8ful... says:
    December 30, 2008 at 1:28 am

    Thanks for this post! Unblocking did the trick.

    Reply
  13. ravi says:
    January 13, 2009 at 3:24 am

    thanks. I was searching for a answer to this problem.

    Reply
  14. christian says:
    February 26, 2009 at 4:43 pm

    thanks to you … easy and fast to open this annoying file

    Reply
  15. Jamie says:
    March 4, 2009 at 12:12 pm

    Thanks! I will add some info about this on my blog as well…

    http://infotechadmin.blogspot.com/2008/12/chm-html-help-file-issues.html

    Reply
  16. faber says:
    May 3, 2009 at 6:49 am

    thank you ;)

    Reply
  17. vishal says:
    May 4, 2009 at 9:30 pm

    thank you… great work

    Reply
  18. Scott says:
    May 15, 2009 at 9:08 am

    Thanks Rob. Fixed it for me.
    Weird that you can run any old DLL you find lying in the gutter, but a help file is considered more dangerous!

    Added link to your page on my blog. Cheers
    http://skotl.blogspot.com/2009/05/downloaded-chm-help-file-shows.html

    Reply
  19. ahmed says:
    May 16, 2009 at 3:30 am

    Thank you so much, works for me.

    Reply
  20. booliolio says:
    July 26, 2009 at 7:21 pm

    w00000t thanks i thought those ebooks were corrupt but now i got them back thanks to you thanks!

    Reply
  21. Phil says:
    August 5, 2009 at 9:11 am

    Thanks so much! I couldn’t figure out what was wrong, I’d never seen that feature before.

    Reply
  22. rusher says:
    August 15, 2009 at 11:15 pm

    nice thanks

    Reply
  23. Jothi says:
    September 21, 2009 at 7:29 am

    Gr8..Thx buddy :) ..it helped me

    Reply
  24. Manoj says:
    September 24, 2009 at 9:09 pm

    NIce post dude

    Reply
  25. shawty says:
    September 27, 2009 at 10:41 pm

    Hi Guys,

    Which of your patched do I need for the following?

    When I view CHM’s off my local hard drive they work fine, but when I attempt to open them of a shared folder on a different server they fail with the content not found pane showing.

    Unblock only shows up when I right click on a local file, and not on the remote file.

    Since I trust the servers I’m storing these files on, I’d like windows to just open them and view them from the \\server\folder\file.chm path in the same way as they open from C:\folder\file.chm

    Reply
  26. Rob says:
    September 28, 2009 at 12:33 am

    So the work around to this security fix is here:
    “CHMs no longer work on the Intranet or Internet”
    http://helpware.net/FAR/far_faq.htm#kb_OpenCHMs

    I usually put the following into a .REG file and double-click the file to put the fix into the registry.

    REGEDIT4
    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp]
    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]
    “MaxAllowedZone”=dword:00000001

    Reply
  27. shawty says:
    September 28, 2009 at 7:56 pm

    Thanks Roy.

    I also found a program called HHReg which makes it easier to add/remove those folders restrictions in the registry.

    I understand why MS have done it, but I think it’s a little stupid how theyv’e done it. In most cases we trust the machines on our Intranets.

    I have a whole server that acts as a digital Library, and this has gone and caned half of the collection now, so I need to find and build a different way of delivering them.

    Oh well… Thanks for your help anyway :-)

    Reply
  28. Rob says:
    September 29, 2009 at 3:18 am

    Yep you need to tweak the registry on ever PC that needs to access the server. Or do distribute the .reg file to all to make that easier.

    The alternative is just to use HTML help. Our FAR tool can make Uncompressed (web) help where TOC, Index & Search are all handled using JavaScript. Here are some examples.
    - http://helpware.net/FAR/help/hh_start.htm
    - http://webhelp.esri.com/arcgisexplorer/900/en
    - http://webhelp.esri.com/arcgisexplorer/900/ja-JP

    Reply
  29. javed says:
    October 12, 2009 at 4:58 am

    Gr8 solutions .. thanks a lot man .. nice work..

    Reply
  30. zacitana says:
    October 23, 2009 at 5:43 pm

    thank you for the post, i was about to delete some of my books but they’re working just fine now :-)

    Reply
  31. Firoz says:
    December 1, 2009 at 5:08 pm

    That was easy… Thank you :)

    Reply
  32. Sanchay says:
    December 26, 2009 at 8:28 pm

    Clicking on Unblock in properties of the CHM files does the job.

    Thanks a ton.

    Reply
  33. Scott says:
    February 3, 2010 at 7:21 am

    Thanks a lot, worked a treat!

    Reply
  34. LindaM says:
    February 4, 2010 at 10:48 am

    Thank you, thank you, thank you.

    I’ve been away from RoboHelp for a while and just got a call for an assignment to create a help file. I mailed my sample file to myself first — just to be sure everything was still OK — and ran into the “Navigation to the webpage was canceled” message.

    Thanks to your post, I was able to give the client instructions for viewing the file and sent it off.

    Thanks again!

    Reply
  35. Dudee says:
    February 19, 2010 at 2:58 am

    Thanks!

    Reply
  36. Remier says:
    March 3, 2010 at 8:14 pm

    Use both keys (32 bit/64 bit)

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\HHRestrictions]
    “MaxAllowedZone”=dword:00000001
    “EnableFrameNavigationInSafeMode”=dword:00000001

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]
    “MaxAllowedZone”=dword:00000001

    AND for 64bit (W2K8R2)

    [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\HTMLHelp]

    [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\HTMLHelp\1.x]

    [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\HTMLHelp\1.x\HHRestrictions]
    “MaxAllowedZone”=dword:00000002

    [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\HTMLHelp\1.x\ItssRestrictions]
    “MaxAllowedZone”=dword:00000002

    Reply
  37. queuety says:
    August 13, 2010 at 3:20 pm

    thanks! saved my time.

    Reply
  38. Dhanil says:
    August 25, 2010 at 6:18 pm

    Thank you very much!!!!!!

    Reply
  39. Vlad says:
    August 27, 2010 at 3:37 am

    Thank you!!! This instantly solved my problem.

    Reply

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