I did a test creating a new file, and returns as boolean, is giving error in return.

Follows the message owncloud.log: 

{"app":"PHP","message":"Call to a member function Create() on a non-object at C:\\xampp\\htdocs\\owncloud4\\apps\\files_external\\lib\\swift.php#431","level":3,"time":"2014-03-27T00:31:26+00:00"}