I upgraded my Mac a few weeks ago to 10.10.2 Yosemite, and I joined the Adobe cloud so I could get access to all the new apps. I read a blurb somewhere about converting older InDesign files to the new CC version I'd have to open the old files in my old InDesign CS3, export to an ins file, then open that file in the new InDesign CC, then export it again to an idml file, then open that file and you shouldn't have any of the usual conversion problems. For the first few files I had to convert, it worked just fine. Now for some reason, whenever I try to open one of these converted files just by double-clicking on the file itself, I get an error message that says, "The document ____ uses one or more plug-ins which are currently not available on your system. Do you want to open anyway?" When I click OK, then I get another error message that says, "Cannot open ____. Please upgrade your plug-ins to their latest versions, or upgrade to the latest version of Adobe InDesign." I thought this CC version of InDesign was the newest. Can somebody please tell me what gives with this? Any help will be very much appreciated.
Did you reinstall CS3 after CC?
For that matter, doing an in-place upgrade on the OS is always a gamble with Adobe programs. Reinstalling all the versions you need, in order, would probably solve your problem.
And you shouldn't need to save as IDML after opening the .inx in CC.