Bulk API issue with contact imports

Question

Is the bulk API having validation issues? I can update any existing or create any new imports.
Simply posting the content below from the tutorial now results in a validation error:
"name": "Docs Import Example",
"fields": {
"firstName": "{{Contact.Field(C_FirstName)}}",
"lastName": "{{Contact.Field(C_LastName)}}",
"emailAddress": "{{Contact.Field(C_EmailAddress)}}"
"identifierFieldName": "emailAddress",
"isSyncTriggeredOnImport" : "false"
Here is the error:
"failures":[{"field":"identifierFieldName","constraint":"Must be a string value, at least 1 character and at most 100 characters long."},{"field":"name","constraint":"Must be a string value, at least 1 character and at most 100 characters long."},{"field":"fields","constraint":"Is required."}]}

Answer 1

Seems like an issue with UD_ADUSER_LOCKED field value. Change it to non null value and retry.