iTunes could not sync calendars because sync server failed

  1. Disconnect your device from your computer
  2. Restart the computer
  3. 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
  4. Connect iPhone to computer and open iTunes
  5. Click your device icon
  6. Go to Info section and tick the boxes for contacts and calendars
  7. Apply