Hope you are doing well and sorry to keep you waiting. As described you are unable to open the PDF file and getting the above said error
Is this a behavior with a particular PDF file or with all the PDFs that you try to open? Please try to open a different PDF file and check.
If the file is located on a shared network/drive, please try to download it to your computer first and then try to open it and check.
You may also try to turn off the protected mode for testing (Windows Only). Go to Edit > Preferences > Enhanced Security > Uncheck 'Enable protected mode at start up' turn off the protected mode and uncheck Enhanced Security > Click OK and reboot the computer.
Note: Please turn on the security after testing to avoid any security risks.