1. Quit Acrobat DC/Acrobat Reader DC application if it's already running.

  2. Download AcrobatNGLEnableTool.zip from https://helpx.adobe.com/content/dam/help/en/acrobat/kb/troubleshoot-activation/jcr_content/main-pars/download_section_cop/download-1/AcroNGLEnableTool.zip and extract file.

  3. Open Terminal, and run the following command:

    $ chmod 775 <Path to the tool>

  4. Right click/two-finger click the extracted AcrobatNGLEnableTool in Finder and select 'Open', then confirm that you wish to open the file when the dialog box appears.

  5. Reopen Acrobat, the issue should now be resolved.



https://helpx.adobe.com/acrobat/kb/troubleshoot-activation.html