Currently Being ModeratedOct 26, 2013 11:05 AM (in response to Paul Hughes5)
How are you attempting to open the older library? If you drag and drop the library onto the 3.4 application, does it open that way? If you option+click when launching Aperture 3.4, and then choose the library from the list provided in the dialog that will appear, does it open? Are you trying to Switch to another library from within the application?
Currently Being ModeratedOct 26, 2013 3:14 PM (in response to Paul Hughes5)
You can't import an older library, it has to be updated first.
Your best bet is copy the library to the system where you want it. Then double click it, Aperture will offer to upgrade it.