If when viewing a preview of a PDF you see the following message:
Select A File To Preview
...you may have a browser or some other non-previewable viewer set as your default PDF Previewer.
We recommend firstly to use Foxit PDF (quite a few users have issues with Adobe PDF of late) - install that if you haven't already:
https://www.foxit.com/pdf-reader/
Then open Foxit PDF (just open any PDF at all - double click on one in DMS if that's easiest).
Go to Help -> Set To Default PDF Reader
Close Foxit
Close DMS and re-open it to check Previews are now working.
Note: please attempt this even if you have freshly installed Foxit PDF and selected it to be the default PDF reader during that install. We have found it can be necessary.
