2.57 to 2.58 update no structural objectClass in configuration table

Hi all, After 2.57 to 2.58 update, slapd refuses to start. OS is FreeBSD 12, slapd built from ports. No clue what is missing, the system ran for two years without a clitch during updates. Thanks! 60bde84c ldif_read_file: read entry file: "/usr/local/etc/openldap/slapd.d/cn=config/olcDatabase={1}mdb/olcOverlay={0}syncprov.ldif" 60bde84c => str2entry: "# AUTO-GENERATED FILE - DO NOT EDIT!! Use ldapmodify. # CRC32 97cb42e9 dn: olcOverlay={0}syncprov objectClass: top objectClass: olcSyncProvConfig olcOverlay: {0}syncprov olcSpCheckpoint: 100 10 structuralObjectClass: olcSyncProvConfig entryUUID: 8ed9549c-5ee4-1036-9903-fd364e50deb0 creatorsName: cn=config createTimestamp: 20161225115355Z entryCSN: 20161225115355.953738Z#000000#000#000000 modifiersName: cn=config modifyTimestamp: 20161225115355Z " 60bde84c >>> dnPrettyNormal: <olcOverlay={0}syncprov> => ldap_bv2dn(olcOverlay={0}syncprov,0) <= ldap_bv2dn(olcOverlay={0}syncprov)=0 => ldap_dn2bv(272) <= ldap_dn2bv(olcOverlay={0}syncprov)=0 => ldap_dn2bv(272) <= ldap_dn2bv(olcOverlay={0}syncprov)=0 60bde84c <<< dnPrettyNormal: <olcOverlay={0}syncprov>, <olcOverlay={0}syncprov> 60bde84c <= str2entry: str2ad(olcSpCheckpoint): attribute type undefined 60bde84c UNKNOWN attributeDescription "OLCSPCHECKPOINT" inserted. 60bde84c >>> dnNormalize: <cn=config> => ldap_bv2dn(cn=config,0) <= ldap_bv2dn(cn=config)=0 => ldap_dn2bv(272) <= ldap_dn2bv(cn=config)=0 60bde84c <<< dnNormalize: <cn=config> 60bde84c >>> dnNormalize: <cn=config> => ldap_bv2dn(cn=config,0) <= ldap_bv2dn(cn=config)=0 => ldap_dn2bv(272) <= ldap_dn2bv(cn=config)=0 60bde84c <<< dnNormalize: <cn=config> 60bde84c <= str2entry(olcOverlay={0}syncprov) -> 0x8013a5e48 60bde84c => test_filter 60bde84c PRESENT 60bde84c => access_allowed: search access to "olcOverlay={0}syncprov,olcDatabase={1}mdb,cn=config" "objectClass" requested 60bde84c <= root access granted 60bde84c => access_allowed: search access granted by manage(=mwrscxd) 60bde84c <= test_filter 6 60bde84c : config_add_internal: DN="olcOverlay={0}syncprov,olcDatabase={1}mdb,cn=config" no structural objectClass in configuration table 60bde84c config error processing olcOverlay={0}syncprov,olcDatabase={1}mdb,cn=config: 60bde84c send_ldap_result: conn=-1 op=0 p=0 60bde84c send_ldap_result: err=65 matched="" text="" 60bde84c slapd destroy: freeing system resources. 60bde84c syncinfo_free: rid=131 60bde84c slapd stopped.