I have setup my calendar (Mountain Lion) to sync with google calendar, and it loads all items in without problems. But when I change something locally, I get an error message:
Access to “New Event” in “XXXXXX” in account “Google” is not permitted. The server responded: “403” to operation CalDAVMoveEntityQueueableOperation.
This happens whenever I do local changes, confirm an event or add a new event.
Everything else is working nicely, including contacts.
Googling did only yield information about this error in relation to iCloud, which I am not using for calendars.