XYplorer Beta Club

If you already have more than 1 installed PDF handler, you will find the GUIDs of currently available preview handlers under this registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\PreviewHandlers

Also be aware PDF X-Change Editor and Viewer are different GUIDs

You can also use this app to find them: http://www.nirsoft.net/utils/shexview.html

A similar problem was resolved here by checking and unchecking the box in UDPH settings after a re-install of the PDF app:
viewtopic.php?f=2&t=19314#p161488

Thanks, ok i get it.
In fact i've done a minimal install of PDF viewer and uncheked shell extension ...
So i just reinstalled with this option checked and it's ok.
Cheers !