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ERROR_DS_OBJ_CLASS_NOT_DEFINED
The requested object class is not in the active schema
ERROR_DS_OBJ_CLASS_NOT_DEFINED is returned when an operation names an object class that the domain controller cannot resolve in the active AD DS schema. It is commonly seen during an LDAP add, an object-class update, or application startup after a component assumes that a custom schema extension is already present.
The usual fault is not a malformed object instance. The first question is whether a matching classSchema definition exists and is active on the particular domain controller receiving the request.
Evidence to collect
- Query the schema naming context using the intended
lDAPDisplayName; do not confuse it with a display name, acn, or a product documentation label. - Confirm that the extension was installed in this forest and that schema replication completed before clients were switched to the new class.
- Verify the client-side spelling and case-insensitive LDAP name mapping, including generated LDIF templates and configuration variables.
- When an application supports multiple editions, verify that the schema extension belongs to the installed version rather than a newer integration package.
What comes next after the class is found
Resolving the class only proves that the name exists. The directory will still validate its superclass, category, mandatory attributes, allowed attributes, and RDN rules before it creates an instance.
References
- Microsoft: classSchema objects in the schema container
- Microsoft: LDAP class names and class inheritance
- RFC 4512: LDAP object-class descriptions
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