Realtoroftheyear Said:
"PDF files from electronic signature software encrypted by MacBook Air: Thank you for your suggestion but I have contacted the developer on several occasions and they say it is an Apple issue....Apple encrypts the pdf docs. I've also spoken to Apple Tech Support on multiple occasions and they offer suggestions but their solutions don't work every time."
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Troubleshooting Third-Party Encryption Apps:
A. Add the App Back:
Uninstall this app and add it back. Encryption is performed through this app, though encryption process it through the macOS. Get this from the App Store or from the Developer, as a way to avoid scams.
B. Single-Out this Device:
Have access to another Mac? If so, install this on the other Mac, seeing if you get the same issue. If so, then it is an issue would you original Mac. If so, then it is an issue with the app itself.
C. Single-Out this User:
Create anew Administrator User, and then see if you get this error. If not, then it is an issue with your current user account. If not, then it my ban an issue with the entire macOS.
D. Reinstall the macOS:
How to Reinstall the macOS:
Nothing would be lost. It's just that misplaced items would be placed back to where they should be and corrupt system files would be replaced by clean files. Go Here: Reinstall macOS - Apple Support. Important: Prior to installing an update or performing a reinstallation, to prevent data loss, be sure to back up your Mac with Time Machine.