Internal server error when starting owncloud rockon in 3.8-15


I get the following message after a fresh 3.8-15 install with new shares after the installation of owncloud rockon:

Internal Server Error

The server encountered an internal error and was unable to complete your request.
Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.
More details can be found in the server log.

The installation finishes without error, and the message above appears in a new blank browser page (instead of owncloud). Any ideas?