751e44c4__Error_Codes___ServiceNow_Wiki__Description
[Error / Data Code] 19 [Error] LDAP_CONSTRAINT_VIOLATION [Description] 
Indicates that the attribute value specified in a modify, add, or modify DN operation violates constraints placed on the attribute. The constraint can be one of size or content (string only, no binary).
LDAP Error Codes - ServiceNow Wiki
Description