What does Windows error code 8321 (ERROR_DS_SINGLE_VALUE_CONSTRAINT) mean?

 
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ERROR_DS_CANT_ADD_ATT_VALUES ERROR_DS_RANGE_CONSTRAINT

ERROR_DS_SINGLE_VALUE_CONSTRAINT

The attributeSchema object permits only one value

LDAP supports both single-valued and multi-valued attribute types. Active Directory records that characteristic in the attribute schema. This result occurs when the resulting entry would hold multiple values for an attribute whose schema marks it single-valued. The conflict can be in an Add request or in a Modify operation that adds a second value without replacing the existing one.

Read the current attribute before deciding how to repair the operation. A client that blindly issues an LDAP add-value modification may work for multi-valued attributes and fail here. If the intent is to change the value, use replacement semantics appropriate to the API; if the application genuinely requires multiple values, it needs a different schema design rather than repeated retries.

What to inspect

  • Inspect the attribute schema and confirm its single-value property.
  • Read the existing value before applying a modify-add operation.
  • Distinguish replacing one value from extending a multi-valued set.

References


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