The last couple of days we've been getting "Error 2016" from Google Calendar.
Sadly, Google has decided it will no longer support the free Google to Outlook calendar syncing app.
Google ceased allowing new installations of this as of 2 years ago, but we along with many others were grandfathered into the free service. Now you are required to use Google Apps, a paid subscription based google service if you want to continue to sync Outlook and Google calendars with a google-based application.