You May Receive A “Windows Defender SmartScreen prevented an unrecognized app from running” Warning Message When Installing the Latest PDF Studio Viewer Installation Package.
Product: PDF Studio Viewer 2019
April 27, 2020


While installing the latest published build of PDF Studio Viewer application on Windows 10, you may receive the following warning: “Windows protected your PC: Windows Defender SmartScreen prevented an unrecognized app from starting. Running this app might put your PC at risk.” You may receive this message even though the download package has a valid digital signature signed with a valid certificate for our company Qoppa Software.

Windows Defender Dialog


Microsoft Windows SmartScreen may flag files that were downloaded from the internet that have not built up a long enough history. This warning is a new security feature of Microsoft Windows and should go away after a certain number of days and a certain number of installs.


You can unblock the application by doing the following on the “Windows protected your PC” dialog box:

  • Click on More Info
  • Click Run Anyway