Just to let you know: I got the same error -34. I had enough local disc space but on my 8GB-iPhone 3G I had the option to reduce audio to 124k.
Therefore I believe the problem description is like said before: The update resets this 124-option and crashes because the music does not seem to fit on the phone.
So thanks to olli.v I was able to update my iphone properly... but it didnt work out well. I finally had to reinstall it -- which turned out to be not to bad to do.
olli.v wrote:
This is completely guesswork, but the -34 occurred on my 3G update also. Once it had failed a couple of times, I noticed that the "downsample music to 128k AAC" option had become unselected. I have the whole library syncing activated and there's about 20G of stuff there. When the downsampling is enabled, it gets squeezed to about 12G on the iphone, so it fits. So my guess is that the restoring process didn't think my library could fit on the phone and bailed out.
As to the fix, I didn't write it down so there's bound to be an error here somewhere:
1) BACK UP YOUR BACK UP DIRECTORY in Library/Application Support/MobileSync
Note: there war only one folder in this. I renamed it to deactivate it.
Maybe I should just have copied it? The file-dates all where from a view minutes ago so the folder didnt look like an incremental backup but like one big backup. But I dont know.
BTW: Restoring the folder didnt work so I would bother to much 🙂 (see below).
2) When the restore process once again complains of -34, select the middle choice (which is not cancel and is not retry, something like delete backup)
I did.
3) Now "restore" in the iphone info page
I am not shure which page this is but I think it is the iphone-front-page that you see when you plugin your iphone?
The problem with this: I could not restore to an older backup. I just had an very old iPod backup in this list.
I tried renaming my backup-folder again to its old name but iTunes didnt notice the change after restarting the app.
So I decided to make a fresh install.
I lost some app-data which dont get saved… but apart from that everything is fine afert an hour of config.
Thanks
Regards