I'm using macOS 10.12, a Google account with multiple calendars, and Apple Mail to send/receive email.
When I get invitations from people at work (mostly using Exchange), the emails have an
.ics file attached. When I open these, Calendar will show this error:
The error says:
The URL https://firstname.lastname@example.org/user encountered HTTP error 404. Make sure the URL is correct.
My calendar settings are basically the default; I just selected a different default calendar. (It's not like Calendar will actually use it to create new events when I double-click
.ics files, but that's a different issue altogether.)
I've already tried the steps outlined here:
… by removing the
com.apple.iCal.plist setting and the folders
~/Library/Calendars/Pending Events and
~/Library/Calendars/Incoming. I've also completely removed the Google account from macOS (under System Preferences » Internet Accounts) and set it up again.
Manually creating entries works fine, though.
In the Console, I see that this request is sent:
[com.apple.calendar.store.log.caldav.http] [PUT https://email@example.com@firstname.lastname@example.org/events/040000008200E00074C5B7101A82E00800000000E05A9DEFFB89D3010000000000000000100000000A23C4C41B14D1498935304A002C0654.ics]
Seems pretty normal to me. When I import the same
.ics file in Google Calendar's Web view, it works fine as well.