ERROR_DS_SINGLE_VALUE_CONSTRAINT - 8321 (0x2081)
Multiple values were specified for an attribute that can have only one value.
Updated: Feb 21, 2026
Technical Meaning
The error ERROR_DS_SINGLE_VALUE_CONSTRAINT with the numeric code 8321 and hex code 0x2081 indicates that a single-valued attribute was provided multiple times during an operation. This error is commonly encountered in directory service operations, particularly when dealing with Active Directory attributes.
Error Details
This error occurs when an application or API attempts to set a property on an object where the property is defined as having only one value but more than one value is specified. For example, if an attribute such as userAccountControl (which typically has predefined values) receives multiple values in a single operation, this error will be returned.
Usage Context
This error is relevant to operations that modify directory service objects, especially those involving Active Directory. It can occur during LDAP operations or when using the Windows API for directory management tasks.
Developer Interpretation
When encountering ERROR_DS_SINGLE_VALUE_CONSTRAINT, developers should ensure that attributes being modified are correctly specified with a single value. This error suggests that there is an issue with the input parameters provided to the operation, specifically related to attribute constraints.
Related Errors
- ERROR_DS_MULTIPLE_OBJECTS_FOUND: Occurs when multiple objects match the search criteria but only one object was expected.
- ERROR_DS_ATTRIBUTE_OR_VALUE_EXISTS: Indicates that a specified attribute or value already exists in the directory service and cannot be added again.
FAQ
Q: What does ERROR_DS_SINGLE_VALUE_CONSTRAINT mean?
A: It means that an attempt was made to set a single-valued attribute with multiple values, which is not allowed by the schema definition of the attribute.
Q: How can I avoid this error?
A: Ensure that attributes being modified are specified with only one value. Check the schema documentation for specific attribute constraints and validate input parameters accordingly.
Summary
ERROR_DS_SINGLE_VALUE_CONSTRAINT is a specific error indicating an attempt to set a single-valued attribute with multiple values, which violates the attribute's definition in the directory service schema. Developers should carefully validate their input parameters to avoid this error.