How to fix “Calendar can’t save the event …to the Exchange server” in iCal in Mac OS X

“Calendar can’t save the event … to the Exchange server. There was an error attempting to send your changes to the exchange server” – I faced this error in iCal for my Exchange calendar with three options (Revert to Server, Try Again or Ignore) and was unable to Save Calendar to Exchange Office 365 in iCal in…