When I try to copy highlighted content into the clipboard, I get an error message "Beim Kopieren in die Zwischenablage ist ein Fehler aufgetreten. Es ist ein interner Fehler aufgetreten" ("An error occured while copying into clipboard. An internal error occurred")
When I try to print the document, nothing happens, not even an error message.
Hope you are doing well and sorry for the trouble. As described you are unable to copy text into clipboard or print the PDF file.
Is this a behavior with a particular PDF file or with all the PDFs ? Please try with a different PDF file and check
What is the version of the Acrobat DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version installed. Go to Help > Check for updates and reboot the computer once
Also please try to repair the installation (Win Only) go to Help > Repair Installation and see if that fixes the copy issue.
For printing issue, please check for any missing/pending updates for printer driver and firmware and try updating them and check.