Do you also have similar issues with synching specific calendars?
The only way for me to synch one of my google calendar is to remove the account and add it back again…
the error also comes from:
Request{method=PROPFIND, url=https://apidata.googleusercontent.com/caldav/v2/XXX%40gmail.com/events/, tags={}} <?xml version='1.0' encoding='UTF-8' ?><propfind xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav"><prop><resourcetype /><current-user-privilege-set /><displayname /><CARD:addressbook-description /><CARD:supported-address-data /><CAL:calendar-description /><n0:calendar-color xmlns:n0="http://apple.com/ns/ical/" /><CAL:supported-calendar-component-set /><n1:source xmlns:n1="http://calendarserver.org/ns/" /></prop></propfind>
while the HTTP response code is also 401…