I can't get the stock Calendar app to open. It shows the "What's New in Calendar" window for a few seconds before going to a typical "Calendar quit unexpectedly" popup.
The crash log mentioned the following:

The crash log mentioned the following:
Application Specific Information:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'
terminating with uncaught exception of type NSException
abort() called