Q: Aperture 3.4 crashes on startup how do I downgrade?

No.  Deleting and/or renaming the .plist file is not the fix.  See Clem's advice below about re-installing Aperture.  I would recommend trying that instead, as it _is_ the fix ;-)

So if you follow Clem's advice, did you re-enable Facebook in Aperture and does it work without crashing?

Thanks, it solved my crashes too

Deleting the "com.apple.Aperture.plist" solved my problem...Facebook account now active in both Aperture and iPhoto and working as expected.

Did the plist thing (sorinfromtotonton) and all started OK although not reenabled facebook yet.

Cheers for this, was driving me mad this morning!

Your solution worked a treat.

thanks again

I've also done the plist thing, and it worked!

Cheers, sorinfromtotonton!

Reinstall from dvd and updates to 3.4 worked for me. Thanks!

Reinstalling from the DVD is all well and good, but if you've been using Aperture since version 2, as I have, you've got to reinstall three separate DVDs to get to version 3.

I would recommend trying the .plist first. Reinstall only if the .plist method doesn't work for you. There are two reasons:

1. It is much faster. It takes all of 60 seconds to do it

2. It probably preserves much more of your customizations than re-installing everything (this is an educated guess only, since I did not test the re-install method)

If you have lots of time to spare and do not mind loosing customizations, by all means, use the SMM (Standard Microsoft Method = reinstall everything ... ;-)  ).

As for the other part of the comment, the "too many versions" is at best a lame excuse. Even more so when Apple FULLY controls the entire chain: hardware, OS and application. I can see this excuse being somewhat acceptable when we talk about Open Source/Linux or especially Windows, where nobody really controls anything. Even there, I would expect such severe defects to be caught in the developer's QA phase.

This is not Apple bashing. It is a flag raised after watching this trend for quite some time now. We had major issues after the Lion upgrade and it took us a long time to make Aperture usable again.

Reinstalling from the physical media fixed it for me too, but only after moving the Aperture application to the trash prior to the re-install. Doing the re-install withouth moving it to the trash first did not fix the problem for me.

The problem is definitely Facebook related, and removing the plist is really NOT the solution if you want to continue sychronizing with Facebook.

Removing .plist removes all user preferences.

Reinstalling aperture does not affect user preferences.

I should mention that I did NOT re-enable Facebook after the .plist method. I agree that the problem is Facebook related. For me, the Facebook link is not important so I will wait for a fix from Apple before re-enabling.

Yes, deleted .plist and everything SEEMS to work. Let's cross fingers…

Deleting the .plist worked for me too!  Thanks.

I'm running 10.8.2 on MBP(mid 2010)