Apple's defaults for Google calendars will fill your console with errors. Configuring your Google account manually as a CalDAV account will fix this right up. Read on for directions.
By Matthew Malinowski, 2013-04-15
This is for OS X 10.8.3.
I was poking around in the Console trying to fix a problem with Chromium and I noticed a bunch of CalendarAgent errors, like this one:
2013/4/15 9:38:06.180 AM CalendarAgent: AOSKit ERROR: (-) RAF: Invalid url -- https://firstname.lastname@example.org/calendar/dav/foo%40gmail.com/events/
I use Calendar.app for scheduling stuff on the desktop, and I still have a few calendars on my personal Google account -- I haven't been able to find any decent alternative calendar services besides iCloud.
Some poking around about this error revealed this tremendously helpful post by Nuno Bettencourt. The short version is that either Apple or Google are following the wrong standard for CalDAV here, and if you create your calendar account in System Preferences, it will use a bad username.
The following might prevent you from syncing contacts, and it might not work with Apps accounts.
As per Nuno, to resolve this error:
For a bit more detail from Nuno and for feedback/caveats from other users, check out the thread on Google Product Forums.