the user_ldap module is missing in the folder app/ since the update 10.0.4. I've also downloaded 10.0.4 manually to cross-check. did you remove this by purpose? how can i get it back? any client login is broken currently.
downloading the latest version from https://github.com/owncloud/user_ldap worked. but still the question remains why the app has been removed from the distribution...
The app was moved to the marketplace https://marketplace.owncloud.com/apps/user_ldap and is not bundled with the main tarball any more. This is to make it possible to update the app independently from core and provide faster updates.
I assume you upgraded from an OC version before OC 10. The occ upgrade should have given you hints about the need to manually install user_ldap from the marketplace.