A variant of the solution proposed here worked for me:
- Quit any and all running calendar applications
- In the "Internet Accounts" System Preferences pane, disable the "Calendars" checkbox of your exchange account
~/Library/Calendars/Calendar Cache*to the Trash
- Re-enable Exchange calendars in the System Preferences.
I initially tried just emptying the Trash, but the calendar files continued to be in use, presumably by the "Calendar Agent" background process. I could have killed the process, but went with a reboot anyway.