An Apple knowledge base article may help solve an issue with syncing in iTunes (versions 7, 8, and 9). The problem occurs when attempting to sync your iPhone or iPod touch with your Mac. Some users also report that the issue arises when attempting to sync their AppleTV.
Apple Support Discussions user "Gavin Cairns" writes:
Using iTunes v.9.0.2 music syncs properly to my iPod touch with 3.1.2, but photos and films will not sync. Backup completes but then the sync stops with the warning:Workaround solutions for this issue are varied and include ASD user "Tom Hensley1" suggesting:"The iPod cannot be synced. An unknown error occured (-50)".
An quicker easier, although bulkier, workaround would be to export all your iPhoto pix to one bit humungous folder and sync your device to that rather than the iPhoto library itself. Annoying and a giant waste of space, but it doesn't seem Apple is going to fix this anytime soon, so maybe it's worth it.This Apple knowledge base article may be the best hope for a solution. The basic overview is to completely delete your current network settings and rebuild your preferences for connecting.
- From the Finder menu bar, select Go > Go to Folder... (or Command + Shift + G).
- In the Go to Folder box, type: /Library/Preferences/SystemConfiguration and click Go.
- In the Finder window that pops up, locate the file named: NetworkInterfaces.plist and drag it to the Trash.
- Restart your Mac.
- When your Desktop reappears, open System Preferences and select Network.
- In the Location: drop down menu, select Edit Locations.
- Click the (+) button and create a new location for your Mac. Apply any special settings that may be required by your connection and attempt to sync your devices.