I was opening my Programming C#, 3rd Edition ebook from O’Reilly in .CHM file extension with my Windows 7 and found that the file was just like blank pages. No text neither images. Like this one:

.CHM file error

This isn’t something I expected. I tried to click another chapter and nothing changes. Searching for the solution, someone said that I need to ‘unblock’ the file from the properties of the file. But, when I look at the properties there’s no such thing like ‘Unblock’ button.

There's no 'Unblock' button.

Confused about 20 minutes, I found –finally– the solution from Microsoft Support said that the problem is the filename.  The filename of my .CHM file is “Programming C#, 3rd Edition.chm” which has the ‘#’ character. I changed the filename to “Programming C-sharp, 3rd Edition.chm” and finally, I can read the book.


Oh, and you can’t use the ‘#’ as the folder name for .CHM files. :)