We did an upgrade of our xwiki server.
We installed a new server and imported the old database in into the new server.
After the upgrade everything looks fine, but in the administer wiki the user,group, rights content is not visible.
The information is available, because I can login with the existing users, I can access the user profiles etc. Also new users are not visible.
If the “old database” includes standard XWiki pages (that define the XWiki UI) then by importing them into the new server you have probably overwritten the 9.11.1 version of them causing a mess. The recommended way to do the upgrade is through the Distribution Wizard http://www.xwiki.org/xwiki/bin/view/Documentation/UserGuide/Features/DistributionWizard .