Horizon requires login for accessing user management as admin

Issue

• Accessing the user management [1] redirects to the login page while logged in as admin.
  • If you are logged in as non admin user the access to the identity part is forbidden as it should.
  • If you are logged in as admin, you can access the identity part [2], but not the users subpart [1].

[1] http://X.X.X.X/dashboard/identity/users/
[2] http://X.X.X.X/dashboard/identity/

• Getting redirected when trying to access the users page in horizon
• Seeing Non-default domain is not supported error message in the keystone.log:

2016-06-08 05:08:35.390 17834 WARNING keystone.common.wsgi [-] Authorization failed. Non-default domain is not supported (Disable debug mode to suppress these details.) (Disable debug mode to suppress these details.) from X.X.X.X