For example, if you are adding "cn=bob,dc=domain,dc=com" and you get:

  ldap_add: No such object

The entry "dc=domain,dc=com" likely doesn't exist. You can use ldapsearch to see if does exist:

  ldapsearch -b 'dc=domain,dc=com' -s base '(objectclass=*)'

Note: if the entry being added is the same as database suffix, it's parent isn't required. Ie: if your suffix is "dc=domain,dc=com", "dc=com" doesn't need to exist to add "dc=domain,dc=com".

For example, if your database suffix is "dc=domain,dc=com" and you attempt to add "dc=domain2,dc=com", "dc=com", "dc=domain,dc=org", "o=domain,c=us", or an other DN in the "dc=domain,dc=com" subtree, the server will return a "No such object" (or referral) error.

slapd(8) will generally return "no global superior knowledge" as additional information indicating its return noSuchObject instead of a referral as the server is not configured with knowledge of a global superior server.