I have found an workaround for this issue. Do the following:
- First, upgrade the library to version 3 using Aperture on the computer where you have the disk containing the library; if this is not possible, copy the library on the computer running Aperture and do the update there, then copy the updated library back;
- Then navigate to the network disk where you have the updated library and double-click it: a dialog box will come out saying something like <There was an error opening the database for the library "/Volumes/Media/Pictures/Aperture Library.aplibrary". The library could not be opened because the file system of the library's volume is unsupported> Click OK.
- A new dialog box will appear asking "Which library do you want Aperture to use?" and a list with all libraries; among them, the library situated on the network disk. Select it and click "Choose".
- Voila, after a delay depending on the speed of your network and remote disk, the library will open.
Note that this "show" will repeat each time you will start-up Aperture. Anyway, it's better than nothing. I hope that Apple will correct this soon.
And yes, I am using the Trial Version, I will buy a license only after Apple solves this issue!