The iPhone [name] could not be synced because the sync session failed to start

I started seeing this error after "upgrading" to iOS7.  There were lots of suggestions on the Net but this is the one that worked for me:

• Close iTunes and disconnect all iOS devices
• Open Terminal
• Go to /var/db/lockdown
• rm * (remove the contents of the folder, not the folder itself)
• Relaunch iTunes and reconnect your iOS device

iOS5: The iPhone ... Could not be synced because the sync session failed to start

iOS5 continues to be a problem.  One of the main complaints is an error encountered when attempting to sync an iPhone or iPod to iTunes:

"The iPhone [device name] Could not be synced because the sync session failed to start"

Several work-arounds have been suggested including simply restarting the iOS device. One procedure that seems to work well is to remove the device backups from iTunes.  Before you do this, make sure you backup your backups folder: ~/Library/Application Support/MobileSync/Backup/

• Connect your device and open iTunes
• Go to Preferences/Devices
• Delete all backups
• Click "OK"
• Restart iTunes and attempt another sync

Sometimes you may see duplicate backups listed.  I found that by deleting all but one backup also allows the device to sync.

Apple's iOS troubleshooting page has some good tips:  http://support.apple.com/kb/ts2529