same error mssg, same problem: voice memos.
my fix.
1. uncheck sync voice memos in iphone / music tab.
1.5 sync the iphone. confirm that the iphone syncs correctly when sync voice memos box is UNCHECKED.
2. copy out the tracks from voice memos playlist that you want to save. use control-click / right-click to show in finder, copy the track out to a different location (desktop for instance), and rename. then re-import tracks into itunes using the "add to library" command in itunes/file menu
2.5 listen to all tracks on iphone that you have not been able to sync. email these tracks to yourself using the 'share' command in voice memos. this is to ensure that you do not loose any voice memos.
3. delete all voice memos on iphone and in itunes voice memos playlist. in itunes, select them all and go to Edit menu / delete
4. turn on sync voice memos in iphone/ music tab
5. sync iphone again
inexplicably, all of your deleted voice memos may return, as they did for me.
~jeremy