The owncloud client in Debian 8 is too old from the Debian repositories, use the opensuse repository.
Add file: /etc/apt/sources.list.d/owncloud.list
deb http://download.opensuse.org/repositories/isv:/ownCloud:/desktop/Debian_8.0/ /
Install the key
wget http://download.opensuse.org/repositories/isv:ownCloud:desktop/Debian_8.0/Release.key apt-key add - < Release.key apt-get update
http://software.opensuse.org/download/package?project=isv:ownCloud:community&package=owncloud