After a ldap schema was removed (based on this article), there are still some references in your ldap
You find the follwing message, when you use slapindex or slaptest.
~# slapindex WARNING! Runnig as root! There's a fair chance slapd will fail to start. Check file permissions! 5cade2d2 UNKNOWN attributeDescription "OWNCLOUDENABLED" inserted. 5cade2d2 UNKNOWN attributeDescription "OWNCLOUDQUOTA" inserted.
You need to find the references and reload the ldap.
Attention! In large environments this my take a lot of time.
mkdir ldap-backup cd ldap-backup /etc/init.d/slapd stop slapcat > backup.ldif
You can remove the references in the backup.ldif
mkdir DB mv /var/lib/univention-ldap/ldap/* DB ucr commit /var/lib/univention-ldap/ldap/DB_CONFIG slapadd < backup.ldif /etc/init.d/slapd restart