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."

  1. Close all Creative Cloud and Adobe services using Activity Monitor.
  2. Download and unzip this file.
  3. In Finder, go to > Library > Preferences and insert the downloaded and unzipped file (com.adobe.acrobat.pro.DC.plist). Authenticate if necessary. If a file with the same name is already there, replace it with the downloaded file.
  4. Open Terminal, and run this command: sudo killall cfprefsd
  5. Restart the machine.