A: On Mac OS X Lion, it is possible to resolve it by temporarily changing the Gate Keeper security settings under “Security&Privacy” in the system preferences to “Anywhere”. After that you can open the JabRef app. When you have opened it once, you can change the security settings back and you’ll still be able to open the app.
A: We were not able to generate a working version of JabRef 2.11 for Mac OS X. Please use the jar of version 2.11, or look at the newer 3.X versions (which fully supports Mac OS X again).
A: Due to the change of the installer for 3.x it is required to perform a clean install of any JabRef 3.x version. You are required to remove any previously installed JabRef 2.x application from the “Applications” folder. Then you can install the latest JabRef 3.x version with the installer. As soon you are running on any JabRef 3.x version, you can use the installer to upgrade JabRef.
A: To override that, Ctrl + Click instead, and choose “open”, which gives the same warning but the possibility to override it. then you can install.
A: The problem occurs because you do not have Java 8 installed, and the automatic download and installation is somehow failing… It can be downloaded here manually: http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html