When launching Acrobat on a Mac, you receive an error message that includes the words, "The serial number 1591[...] is already in use by the maximum allowed computers."
- Close all Creative Cloud and Adobe processes using Activity Monitor (Finder > Applications > Utilities > Activity Monitor). This would include all processes with the Creative Cloud icon and all processes that begin with Adobe. To cancel, double-click the process and click the Quit button, then the Force Quit button.
- Download and unzip this file.
- In Finder, go to Go > Go to Folder.... Type ~/Library/Preferences and click the Go button. Insert the downloaded and unzipped file (com.adobe.acrobat.pro.DC.plist) into the Preferences folder. Authenticate if necessary. If a file with the same name is already there, replace it with the downloaded file.
- Open Terminal, type sudo killall cfprefsd and hit Enter.
- Restart the machine.