Caution: If your Address Book under v10.5.x includes a Smart Group with a negative condition (e.g., "Card is not a member of any group"), you may have a problem upgrading to Snow Leopard's (v10.6) Address Book. I did.
After the update--which finished in about 45 minutes and ran without any obvious complaint--my Address Book would launch, display there were no cards, and then freeze--necessitating a Force Quit. When I launched Mail, initially it would open looking normal, but then it, too, would freeze. (Once the problem with Address Book was solved, Mail was then OK.) The good news was that, so far, that has been my only glitch with the upgrade.
It took a call to AppleCare--and a long time trying other "solutions"--before the technician found a posting (I believe from some forum, but I don't know whether it was an internal or public forum) noting a problem if there were such a Smart Group in the Leopard Address Book. Having done a SuperDuper! clone, on an external hard drive, of my MacBook Pro immediately before doing the upgrade was part of my game plan and, in this case, was a life-saver.
With the AppleCare technician pointing the way, I re-booted into Leopard from that external hard drive, launched Address Book, and deleted the Smart Group. We then copied the ~/Library/Application Support/AddressBook folder from the external hard drive (after adjusting Permissions, if needed) to the comparable location on my MacBook Pro once it was re-booted from its internal hard drive in Snow Leopard--but we weren't out of the woods quite yet. Address Book would now launch, but it still claimed no cards. (There were, however, the proper 5,000+ cards in the Metadata folder within that AddressBook folder.)
While having deleted the Smart Group within Address Book application under Leopard before copying that AddressBook folder was expected to have deleted all remnants of it, the technician wondered whether that was, indeed, the case. He then had me search that Metadata folder within that AddressBook folder for the Smart Group file by typing "smart" in the search oval as that file's long cryptic name would include "smart"--and such a file was found. (In my case, it ended with "ABSmartGroup.abcdg" [without the quotes].) We deleted that file, re-started the computer, and Address Book was fine. And as noted above, when I then tried Mail, it, too, was fine.
Along the way of trying other things that didn't work (e.g., transferring an Address Book Archive made under Leopard and importing it under Snow Leopard; doing Export Group vCards under Leopard and importing them under Snow Leopard), we found importing Group vCards under Snow Leopard doesn't preserve the Group identification and while, then, hoping to use Snow Leopard's Address Book's "Last Import" Group to identify the last import, we found that Group doesn't properly report just the last import. (The AppleCare technician is reporting those issues within Apple.)
Note: I then, after doing an File->Export->Address Book Archive, tried to recreate that "negative" Smart Group in Address Book under Snow Leopard and that, too, caused a freeze; however, I was able to recover using that Archive.
Hope this helps someone else avoid the problem as, otherwise, I very much like what Snow Leopard--even v10.6--has brought me. (Now if some of my 3rd-party software gets updated for Snow Leopard, things will be even sweeter.)
David
Last edited by cyn; 09/04/09 02:19 PM. Reason: Moved from 'Mac OS X 10.6.x' to the 'Mac OS X Applications' forum because the topic focuses on troubleshooting and solving a problem with Address Book.