This is the first time I've tried to use EV3 software since upgrading to El Capitan. Before then, it worked perfectly.
When I tried to launch the application a message pops up saying it has detected a problem during application launch.
I uninstalled the software, uninstalled the silverlight plug-in.
I installed the latest Silverlight plug-in, see screenshot
I downloaded the EV3 software and tried to install it, but it didn't complete and didn't give much of a useful failed installation message, see screenshot
Interestingly, the silverlight plug-in has now disappeared.