Cannot remove LDAP entry ...

Hello

I have a problem removing ONE ( and only ONE !!! ) entry in my directory server

ldapdelete fails like the following

ldap_delete: Other (e.g., implementation specific) error (80) additional info: entry index delete failed

I've checked online openldap documentation and this error refers to a access rights problem, but it is not the case for my server , all db files belong to ldap:ldap which is the identity the slapd deamon runs on.

the server runs 2.4.23 version on a FreeBSD 8.1-RELEASE-p5 compiled and installed from ports.

ldap# /usr/local/libexec/slapd -V @(#) $OpenLDAP: slapd 2.4.23 (Oct 15 2010 16:35:06) $ root@ldap3.esiee.fr:/usr/ports/net/openldap24-server/work/openldap-2.4.23/servers/slapd

Any help welcome thank you