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ERROR_DS_SCHEMA_NOT_LOADED
Schema-dependent processing started without a usable loaded schema
Active Directory operations depend on a loaded schema model to interpret object classes, attribute syntax, naming rules, and constraints. This status means that usable schema state is not available to the directory operation. It is broader than a missing individual attribute definition: the DSA cannot rely on the schema model it normally uses for validation.
Correlate the error with directory-service startup, schema NC replication, and recent schema cache failures. If a prior schema update failed validation, the more specific consistency or cache error is more useful than this later status. Microsoft describes schema cache recalculation as a blocking operation that rebuilds in-memory state from the schema naming context, so successful cache activation must be verified before ordinary schema-dependent writes are retried.
What to inspect
- Review Directory Service events from startup or the most recent schema update.
- Verify schema naming-context replication and locate earlier schema-validation errors.
- Do not troubleshoot one application attribute until the directory reports a usable schema state.
References
- MS-ADTS: schemaUpdateNow
- Microsoft: updating the Active Directory schema cache
- Microsoft: Active Directory schema terminology
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