---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/520015#article
headline: "520015: Bulk identifier add failed"
url: https://www.twilio.com/docs/api/errors/520015
inLanguage: en
dateModified: 2026-04-01T03:32:01.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 520015: Bulk identifier add failed

Log Type: TWILIO

Log Level: ERROR

## Description

Bulk identifier assignment failed because the file contained unprocessable data.

### Possible causes

* Batch payload contained duplicated or incorrectly formatted identifiers

### Possible solutions

* Execute a strict data validation and refinement step to ensure data cleanliness before uploading the batch payload