Yesterday I've spent hours and hours trying to make the freshly released owncloud 31 play nice with nginx.
The web interface was running correctly, but any kind of DAV access failed. I've tried everything but the closest I've got was an xml error from the Sabre DAV server of the project.
Until I've found a mail archieve from a KDE list from last year October2 saying I need on more fast CGI parameter than ususally.
So to solve the problem add:
into your server config's fastcgi params, and suddenly the sky becomes bluer the bird starts singing and you can start playing with your own cloud.
Thank you very much, Weng Xuetian!