Hope you are doing well and sorry for the trouble. As described, you are unable to open the PDF file and getting the error 'This document cannot be opened. file not found'
Is this a behavior with a particular PDF file or with all the PDFs? Please try with a different PDF file and check. Also, if the file is stored on a shared network/drive, please download and save the file to your computer locally and then try to open it and check.
- Have you created this PDF file or have you got it from a different user and how the pdf is created?
What is the version of the Adobe Acrobat Pro DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version 21.01.20135 installed Go to Help > Check for updates and reboot the computer once and check .