I created a bunch of files using Adobe Creative Cloud, saved files in both .ai and .eps, but have since decided switch to AI CS6.
I am able to open the .ai file versions without a problem, but when I attempt to open the .eps versions, I get a legacy error message. How can I get the .eps files to open? This is the message I get when I attempt to open the .eps file versions.
You must use the version the files were created in and back-save to the older (legacy) version you want to work in.
This is one HUGE issue with Adobe's subscription model.
Also be aware, that when you back-save you may lose editing capabilities for any appearance which uses newer features. New features can not always be supported in legacy versions. So, things can be flattened or expanded when back-saving.
If you no longer have access to Illustrator CC or CC2014, you'll need to resubscribe in order to open the files and back-save them or find someone who will do it for you.