Hi there - Joseph asked me to post this as a new thread, so here it is!

I followed the instructions on the Aperture website to the letter:
It Didn’t Work
This procedure did work for me - of course, it doesn’t come with any guarantee, but as long as you have backed up properly it won’t cause any grief.

Before I describe it one thing I would say is that you shouldn’t expect to use your computer for any very heavy processing while this is going on, and that you should restart it at every possible opportunity (i.e. after each stage).

I tried the proper update routine 3 times, and each time it came up with a message:
*Your Mac OSX startup disk has no more space available for application memory*
despite the fact that there was nearly 200gb free on the hard drive.
This is what I did:

1. made a copy of my Aperture 2 library somewhere else
2. moved the live copy to a different folder
3. Opened Aperture 3 (which then created a new empty library)
4. I opened preferences, switched OFF face detection
5. I switched off ‘New Projects automatically generate previews’
6. Imported my old library (from the different folder)

This was slow, but didn’t freeze the machine, and you could see it working (it took about 8 hours with my 47,000 photo library). Incidentally, I think it’s the number of pictures that’s at issue rather than the size of the library.

When it’s finished importing. _Any fiddling or looking around will likely just freeze aperture_.
*CLOSE APERTURE
REBOOT YOUR MACHINE*

Open Aperture (this may take several minutes, and it may say it isn’t responding - don’t believe it! - you can check in the Applications / Utilities / Activity Monitor if in doubt.

When it’s opened, click on Window / Activity - this will probably tell you that it’s updating the library - with a huge number of properties to update (it was something like 87,000 on mine).

If you want to do anything - then pause this procedure first - if it’s been going for some time, then pause it, close Aperture and restart your machine.

You should do this every 2 or 3 hours anyway (restarting your machine) -(because it’s much much faster after it’s restarted).

It took my computer (17” MBP 2.66 unibody with 4gb Ram and 200gb free on HD) 2 days to do this procedure - now I seem to be cooking.

Of course, there may be many other ways of making this work, and this may not work for you but having tried the proper ‘upgrade’ option 3 times, and it simply didn’t work.

all the best
Jonathan Slack