It seems like the Stable repositories are not available. If I follow the recent documentation to install, this Repo link should work, but it says „file not found“: https://download.owncloud.org/download/repositories/stable/owncloud/
It seems like the stable repository was removed. The other repositories looked good to me.
If my monitoring works correctly the issue occured first in the 60 Minutes before 21:28 2016-08-26.
Maybe someone who is running the repo servers can make an announcement if the repo is going online again or if we have to manage with version numbers in repo links (what wouldn't be that comfortable to me).
Thanks in advance.