As you all know, Apple along with previewing the iOS 5, iCloud and Mac OS X Lion, released an update to the iTunes at their WWDC keynote presentation on Monday, the iTunes 10.3. This update to the iTunes is currently on its beta stage which adds a feature that takes advantage of early iCloud features. But within just days, Apple has released an update to iTunes 10.3 which supposedly fixes some syncing issues.
The new iTunes 10.3.1 update doesn't exactly specify in the change log which are the issues that were fixed and it only list all the features that were included in iTunes 10.3. But this could be somehow related to reports from users that iTunes returns an "unknown error (-50)" when they attempt to sync their devices.
According to some users from the Apple forums:
Same problem here. MacBook Pro 10.6.7, iTunes 10.3, White iPhone. Rebooted the Mac, rebooted the iPhone. No luck still get unknown error (-50) cannot sync. Bummer. My setup has worked flawlessly prior to upgrading to 10.3 iTunes.
This is a me too, Macbook Pro on 10.6.7, iPhone 4 running 4.3.3 and itunes 10.3. As soon as I installed 10.3 tried to sync and got the unknown error -50 error pop up. I tried closing iTunes, reopening and hard booting the iPhone to no avail. Hope this gets fixed soon! Any hints would be really appreciated.
Although there is no known changes documented in the iTunes 10.3.1 and what were the issues addressed, if you have upgraded to 10.3, there is no reason why you shouldn't update to 10.3.1.
iTunes 10.3 introduces a new "iTunes in the Cloud" feature where users can sync purchased content with up to 10 devices max on the fly. This feature is an early part of the new iCloud service by Apple which will be fully operational this coming fall.