I just updated Scrivener to the latest El Capitan-friendly version. When I tried to open up an older project, I received an error report: “The project you are trying to load uses an older file format and cannot be opened. Would you like to update it? A copy of the old project will be saved in the same directory.”
When I select UPDATE, I then get this message: “The update has been cancelled because there was an error when trying to create a backup of the project. Please check there is sufficient space on your hard drive.”
I have loads of space on my hard drive, so this is not the issue. Some of the specs you may be interested in- I’m on a 2013 iMac with Intel processor. I’m updated to the latest version of OSX 10.11.3. The projects I’m trying to work on are kind of old, last modified in March of 2015. I can’t see the version of Scrivener that I was using when I last saved those projects, but it should be the version that was current as of March 2015.