+++ This bug was initially created as a clone of Bug #55884 +++ The diagnostic module shows errors, when a customer uses non-standard prefix for the school admins group (default is 'admins-'). The prefix con be configured with UCRV ucsschool/ldap/default/groupprefix/admins. ucsschool.lib.consistency correctly uses the UCRV in UserCheck.__init__(), but forgets to do that in check_mandatory_groups_exist() -> mandatory_groups[-1]. It should either use the UCRV like in __init__() or better also change that code to use SchoolSearchBase([ou]).admins_group.