Confirmed in HEAD. Unique makes too small buffer for filter "(uidNumber=0)", so build_filter() line 931: assert( len >= 0 && len < ks ); fails because len == ks == 13 == strlen(filter).

slapd.conf: include ...core.schema include ...cosine.schema include ...nis.schema database bdb directory /tmp/db suffix uid=dwhite rootdn uid=dwhite rootpw secret overlay unique unique_attributes uidNumber

'ldapadd'ed ldif: dn: uid=dwhite objectClass: account objectClass: posixAccount uid: dwhite uidNumber: 0 cn: Dan White gidNumber: 1 homeDirectory: /home/dwhite