In our testing, we found no other significant issues with running Creative Cloud products with Mac OS X Yosemite. Explicitly set the Adobe plug-in as the default PDF viewer. When opening a PDF in a browser, Safari's PDF Preview is the default PDF viewer. When using Mac OS X 10.10 with Safari 8, PDFs do not open using the Adobe Acrobat or Reader PDF browser plug-in. While Adobe is signing future updates with V2, some applications that are signed with the older V1 code signing may issue a warning: ' can’t be opened because the identity of the developer cannot be confirmed.' Learn more. Apple has improved security by introducing their new 'V2 code signing' (it is a way to guarantee that the application came from the developer and has not been altered, infected with a virus, or damaged in any way).