I've have owned Adobe CS6 (Master Suite) for years and it always worked fine. Now some apps don't open.
Illustrator and Audition ask if I want to continue the Creative Cloud Trial period, even though I have never tried the Cloud version and I certainly don't want to. Audition says I can continue using the Trial version of Cloud for 32676 days, which is quite generous but weird. Encore asks for my serial number and then rejects it, even though I know it's the right serial number. The point is that many of them are screwed up but in different ways. The one I need most is Illustrator. I have tried uninstalling and reinstalling from my Master Collection original install file -- same results.
Some things (Photoshop and InDesign) work fine but Illustrator is the one I really need right now. How can I get this to work correctly? I'm using Yosemite on a 2014 Mac Pro.
Most likely a Yosemite thing. I just upgraded and I'm having issues and now I'm getting all these little notices and weird errors, though not what you are seeing. Beyond that, check adobe's site. I'm sure this isn't the first time it's happened.