iTunes could not sync calendars because sync server failed
Updated
Disconnect your device from your computer
Restart the computer
Rename SyncServices folder to something different (name doesn't matter). In Windows Vista, 7 & 8, the location of SyncServices is C:\Users\[your computer name]\AppData\Roaming\Apple Computer\ To quickly access the AppData folder: Click Start In the search bar type %appdata% Press the Return key
Connect iPhone to computer and open iTunes
Click your device icon
Go to Info section and tick the boxes for contacts and calendars