Some .chm files do not work on Windows 7 – Process Monitor – Navigation to the webpage was canceled

This took me a couple of minutes to find so I thought I would share this here.

I downloaded ProcMon (process monitor) and could view the help file.  It would open but the right pane had a message: "Navigation to the webpage was canceled"  The left pane was functional however.

I found the help file.  This is a .CHM file stored in the directory where Procmon was installed.

To be able to use is, Right Click on the procmon.chm file and choose 'Properties' from the menu.  Then in the general tab, click on Unblock!  (You may need to run as an Administrator account to see the unblock item).

Works fine now!

 Let me know if you found this useful by dropping me a note please!

Comments (51)

  1. Lashl777 says:

    Thanks!  I unblocked all of the *.chm help files in the Sysinternals Suite folder.  Now ALL of the help files in the Sysinternals Suite work fine!!!

    FYI -When I searched for "help file Navigation to the webpage was canceled" – I clicked on the first result… it took me to "".  I found your solution, but there was NO WAY TO LEAVE A COMMENT.  I clicked around and found that the bold words at the top "Http Client Protocol Issues" took me to all of your blogs with that title.  I could "comment" only from that page.  I am telling you this because I do not think the search should have landed a page without the option to comment – when you in particular are asking for one.  I did notice that this is the only topic on the "Http Client Protocol Issues" page that does not have a "filed under" property.  Maybe that’s why???

  2. Jeff Sanders says:

    You need to be logged in to leave a comment.  I will enable anonymous comments.  Thanks for the feedback!

  3. nobody says:

    I am using Windows Vista Home Premium.  When I try to unblock the file, it seems to let me (the unblock button goes away when I click apply).  However, it puts the block right back on (that is, when I go back to the file and examine the properties, the block is back).

  4. Jeff Sanders says:

    The key to this will be to find out who is changing the file attributes back (AntiVirus maybe).  If you run Process Monitor, Available from, You should be able to deternime who is changing the file attributes back and if you are sucessfully unblocking the files to begin with.  You can search on the file name to see all activity on that particular .chm fine.  Let me know what you can see from the process monitor logs.

  5. Vijay says:

    This helped me. I knew it was blocked from pre windows 7 time frame but had forgot how to unblock. Thanx.

  6. mikewi says:

    When I click on properties I only get a General tab which does not have an Unblock button. Any ideas?

  7. Jj says:

    Thanks worked like charm on my moq.chm file!

    I would just add that you have to right click the .chm file a click "Properties". And then go to the General tab and do the UnBlock.

    I know this sounds silly to most users, but less experienced ones might be wondering where in the menu is General tab.. 🙂


  8. Thomas Kornechuk says:

    I could not find the unblock selection, but resolved the same issue by moving the chm file to the public documents folder.

  9. Tom Ray says:

    AWESOME!  You saved me hours of frustration!  Thanks for posting.  by the way Thomas click on properties after you do the right click and you will see the unblock button on the bottom

  10. Seva says:

    Thanks. It’s simple and easy, and does work for me.

  11. Rick Byrd says:

    I could not find the unblock at first. I am running Windows 7 Professional. To get the unblock to appear I had to run Windows Explorer as Administrator, then when I right-clicked on the chm file the unblock button was available.

    This is the first site I found that mentioned the unblock feature. thank you.

  12. Me says:

    I was playing with the NIRSoft NIRLaucher portable suite [] and got multiple .CHM errors.  I then hit your page about using the "unblock" button, tried ^A / Properties to see that doesn’t show that button, and griped: I’m not fixing all *that* manually.

    And then I suddently remembered how it’s keeping track of this — NTFS streams.  Get SysInternals streams.exe to see which files have what names, and then run more against them, like this:

    23:46:46 streams wul.chm

    Streams v1.56


      :Zone.Identifier:$DATA       26

    23:47:01 more < wul.chm:Zone.Identifier:$DATA



    _SIMON_ _SAYS_ _USE_ _MORE_.  Not type, not copy, notepad, nuthin’ else — MORE.  And you have to get the target fork exactly right or you’ll miss it.  Echo and type will create, but only more can read.  [Update!  gnuwin32 CAT can read and write both!]

    I did a demo on streams at work 2 years ago for our group (IT server support, 20K users) on user hiding MP3 files.  I gave them a directory of random files and said: "There *ARE* 10 MP3 files in this directory.  We’ll talk about it next week but find them before then and I’ll buy you a coke."  No one did — maybe I should have offered a beer instead?

    Anyway, I renamed files and embedded and such, but that was one of the harder tricks I did — I stuck an NTFS stream of an MP3 file on a directory.   And it seemes like foobar or such would play the stream source directly.  So I’d play my favorite annoying (to them) songs and challenge them to stop me.

    In this case I haven’t figured out if ripping the resource fork will fix it (copy to FAT and back) or if I have to replace every single entry with something else.  Using ECHO and COPY will create forks, but apparently MORE is the only intrensic that can read and display them.  

    Good luck!  Thanks for fixing anonymous comments!  And remember, if a GUI commmand can do it, there’s probably a better CLI somewhere else — GUIs aren’t magic, they’re just pretty.

  13. Me says:

    Oh, and says here’s a possible CHM unblock:





    Maybe it works, maybe it formats your C: drive; dunno. [Joke: the reg patch _doesn’t_ format your C: drive.  But if you’ve negated the block and run an infected CHM file, *IT* just might do so.]  

    You picks your poison and you takes your chances.

  14. aoeu says:

    Thanks! helped me get a CHM working.

  15. Jeff Sanders says:

    Update:  The reason for these blocked files is that they are downloaded and installed from the Internet Zone (Security Measure). There are numerous references to Registry and other fixes but don’t use them.  You can copy them off to a FAT drive and then copying them back to a new directory (removing the stream that has this information) or use the sysinternals Streams.exe tool.

    Then you can remove the security info by removing the streams from the chm files by going to a cmd prompt, navigating to the dir with the chm files, ensureing they are NOT marked read only and typing <<Path so streams>>streams.exe /d *.chm

  16. dcornelius says:

    Thanks for this post.  It's old but still shows up high in the search result list and helped me out when I was trying to view ProcessExplorer's help.

  17. keaton says:

    ah thanks, just ran into this issue

  18. MarkJones says:

    Thanks for the answer. Your post was the first I looked at and it was spot on. I was using XP Pro and didn't even know that xp had a block function.

  19. I_C says:

    In my case the Unblock / streams.exe solution was a red herring.

    It turns out that you can't read a .chm when it lives in a directory which has any characters like '#', '?', '&', and '+' in the name. See…/chm-files-the-page-cannot-be-displayed-error

    Solution – just move the .chm file someplace else without a #,?,&,+ etc… in the name. How f%%%ing annoying.

    Weirdly enough the file I was attempting to read was moq.chm which someone else commented on, so you never know, maybe it was doubly screwed and the  streams.exe fix was required after all …

  20. Simon Brown says:

    # I_C

    Thanks, the reason for mine was the # in directory and names. As I had books on C# !!

    Could not see unblock even as Administrator but renaming files to Sharp from # worked a charm

  21. Jeff Sanders says:

    Thanks Simon for publishing your solution so that it may help others!

  22. Vilas Patil says:

    Thanks for sharing this. It worked for me.

  23. Staff says:

    Thanks jpsanders for your great solution. It is much better than the one described in the article.

  24. sand says:

    Thanks, works on windows 8 as well..

  25. Vivek George says:

    Thanks a lot

  26. john says:

    i clicked properties but sill unable to unblock it via clicking unblock tab on win 7.. whts the reason?

  27. Jeff Sanders says:

    Hey @john – You may have to be an administrator on the Machine.

  28. RP says:

    Nice.  I had so much other stuff to do that when the Help didn't work, I just gave up on ProcMon.   Now, a few days later, I had a few minutes and found your blog page.  Now I have Help! Thanks!

  29. Amit Henry says:

    I downloaded a ".chm" file (A C++ tutorial) and wasn't able to view it's contents. So, after lots of disappointment and searching for some solution, I finally came to this site. Just read it for 5 seconds and slapped my head – lol

  30. Sowndar says:

    Yes, it worked. Thanks a lot…. 🙂

  31. …"typing <<Path so streams>>streams.exe /d *.chm.."  That fixed it for me.  Thanks!

  32. Joseph says:

    Streams worked perfect. Many thanks.

  33. Shailendra Singh says:

    Thanks, It worked for me

  34. soliu says:

    Thanks alot. You save me lot of headache when trying to open Python 3.4 ref manual.


  35. Ahmed says:

    Thaaaaaaanks alot.. I am reading the help file now : ) u save me a lot of time

  36. Ram says:

    Thanks this helped me

  37. moka says:


  38. moka says:

    thanks alot

  39. Matthew A. Schneider says:

    I didn't have a FAT formatted drive available, so I copied the file off to the DVD (which is UDF format), and copied back. Now works like a charm, off the DVD too by the way 🙂 Thanks Jeff for pointing the way forward.

  40. Jon Maloney says:

    Thanks! I searched Google for — how to read a chm file in windows 7 — and this page was the 8th search result. Most of the other results were for programs that would read chm files. I thought there was an easy way. I just couldn't remember what it was. Very easy… go to properties and click unblock.

  41. Ken747 says:

    Thanks for taking the time to post this, helped me out  : )

  42. Andrew says:

    Win 7 – I had a similar problem, except the above answers did not work for me. The right pane was blank, no error message displayed. Logged in as an Administrator, but there was no "Unblock" button under Context Menu > Properties > Security.

    My problem was accessing the .chm file on a network share on my NAS. Simply copying the file to a local drive worked OK!

  43. Lodi says:

    Thanks, it work

  44. Robyn says:

    Jeff Sanders – Thank you, all other options were not workingW

  45. Mark says:

    The file must be on a local computer. Not a Network drive.

  46. Christian says:

    Yes, some of our problems actually enjoy a rather simple solution!


  47. Mike says:

    Thanks ever so much…Was completely lost as to why this was happening.

  48. Brad says:

    Perfect!! Appreciate the knowledge share!

  49. Ferruccio_M says:

    Worked fine for me (on a Windows7 professional) via the “Properties” tab, thanks!

  50. flat sheet says:

    Thanks on your marvelous posting! I truly enjoyed reading it, you could be a great author.
    I will make certain to bookmark your blog and definitely will come back later on. I want to encourage one to continue your great work, have a nice day!

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