Notepad++ HTML Tidy

Windows 7-10 x64, Notepad++ 5.9.5 Solution:

It has to do with the libTidy.dll not being included in the current distributions.
However, it was available in earlier versions.

Solution is to download the 5.9 zip, then
copy one of the following folders:
ansi\plugins\Config\tidy or Unicode\plugins\Config\tidy
to your current Notepad++\plugins\Config folder

Also, if you install to the c:\Program Files or c:\Program Files (x86) directories, you will need to adjust the permissions on the tidy folder to allow non-administrator access

All of the menu options except the first one rewrite the HTMLTIDY.CFG file, which specifies the formatting rules that HTML Tidy uses. If HTMLTIDY.CFG does not exist, these menu options may not work.

Create a text file and type a simple instruction like:

text-spaces: 2

Save the file as htmltidy.cfg in %ProgramFiles%\Notepad++\plugins\Config\tidy. Restart Notepad++ and all of the options should work.