When trying so as to add an event someone despatched you to iCal, if you get the error “This calendar file is unreadable. No events were added to your calendar”, here is the repair. retailer the file to your pc (or someplace at hand) and edit it with a text editor like TextWrangler. ensure there aren’t any spaces at first sooner than ‘start:VCALENDAR’ or at the finish after ‘finish:VCALENDAR’. it appears some Outlook events get mangled, even some that come from 10.four and are despatched to 10.5.
more: endured here