We are sorry for the trouble. As described yoiu are getting the error 'Acrobat failed to connect to a DDE server'
Would you mind sharing:
The steps/workflow that you are doing that leads you to this error?
The version of the Adobe Acroat DC you are using? To check the version go to Help > About Adobe Acrobat and make sure you have the latest version 20.12.20043 installed from the help menu > check for updates.
Are you on a Mac or Windows machine and what is the version of the OS?
Is there any security software installed on your machine that might be causing the issue? For testing Purposes try to turn off the security software and check if that makes any difference.