Yes, you have to fix your owncloud as described in #578 (only change of one line is needed)
Alternatively you can wait until OC releases the already submitted patch that fixes this issue!
so in version 1.4 everything was fine. I now have version 22.214.171.124-ose. I use DAViCal with a debian.
My old account’s still work(sync), but when I add a new one it fails recognizing the calendars.
Thunderbird Calendar-Plugin still works and is able to subscribe calendars from DAViCal (old and new)
Ahh and Apache2 listens on 80, 8080, and 443
Thanks for your time
403 Forbidden looks like a server problem …