ERROR_DS_AUX_CLS_TEST_FAIL - 8389 (0x20C5)
Schema update failed: class in aux-class list does not exist or is not an auxiliary class.
Updated: Feb 21, 2026
Technical Meaning
The ERROR_DS_AUX_CLS_TEST_FAIL error indicates a failure in the schema update process. Specifically, it signifies that an auxiliary class listed during the schema modification is either non-existent or not recognized as an auxiliary class.
Error Details
This error typically occurs when attempting to modify the directory service schema and includes validation checks on the classes involved. The presence of an auxiliary class in the list being modified must be verified; if such a class does not exist, or it is not correctly identified as an auxiliary class, this error will be triggered.
Usage Context
This error can arise during operations that involve modifying the directory service schema, such as adding new attributes, classes, or other schema elements. It is particularly relevant in scenarios where auxiliary classes are involved, which often play a role in defining additional properties or behaviors for objects within the directory structure.
Developer Interpretation
Developers should interpret this error as an indication that there is a problem with the schema update process due to invalid class references. This could be caused by incorrect parameter values, missing classes, or misidentification of auxiliary classes during the operation.
Related Errors
ERROR_DS_SCHEMA_NOT_FOUND(0x80072031): Indicates that a required schema element was not found.ERROR_DS_OBJECT_CLASS_VIOLATION(0x8007204D): Suggests that the object class being added or modified does not match the expected structure.
FAQ
Q: What causes this error?
A: This error typically occurs due to invalid parameters, missing auxiliary classes, or incorrect identification of auxiliary classes during schema modifications.
Q: How can I resolve it?
A: Ensure that all class references are correct and exist in the directory service. Verify the schema update process for any misidentifications or missing elements.
Summary
ERROR_DS_AUX_CLS_TEST_FAIL is a specific error indicating issues with auxiliary classes during schema updates. It highlights problems such as non-existent or incorrectly identified auxiliary classes, which can be resolved by validating and correcting the involved class references.