openFile with pandoc 1.13.2 - Windows 8.1
I finally solve my problem by adding the full paths to my files (But I have used wkhtmltopdf which is simpler to use for a good result.)
sorry for my english in my post (it is my first on this forum, and my question is perhaps stupid).
I encounter a problem in converting a html file to pdf file with pandoc.  
Here is my code in the console
set Path=%Path%;C:\Users\nicolas\AppData\Local\Pandoc
(redirecting to Pandoc directory)
followed by
pandoc --data-dir=C:\Users\nicolas\Desktop essai.html -o essai.pdf

As indicated, my file is in the Desktop, but I got the following error:
pandoc: essai.html: openFile: does not exist (No such file or directory)

I get the same error if i do (with the file essai.html in the same folder as pandoc.exe):
pandoc essai.html -o essai.pdf

Have you any idea of the cause of my problem? (I precise that the file's name i want to convert is correct).
Remark: My original problem was to create a pdf faithful to the beautiful html file generated by Ipython Notebook via pandoc but I encounter the same kind of problem when i want to convert a .ipynb file in pdf with nbconvert.