During the upgrade, the default application for opening .pdf files may have been changed to Microsoft Edge vs. Adobe Acrobat. To change the default:
Select the Start button, then select "Settings"
Select the "Apps" option
From "Default Apps" Select the "choose default apps by file type" link
Scroll the list to find ".pdf" then click the Microsoft Edge icon and select "Adobe Acrobat" from the "Choose an app" menu. If you do not have Adobe Acrobat Professional installed on your machine, the app may say "Adobe Reader".
Click the "Switch anyway" link to confirm you want to make the change.
All of your .pdf files will now open in Adobe Acrobat.