---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/21231#article
headline: "21231: Domain Validation Error"
url: https://www.twilio.com/docs/api/errors/21231
inLanguage: en
dateModified: 2025-12-18T21:40:49.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 21231: Domain Validation Error

Log Level: ERROR

## Description

One of the parameters passed when creating or updating a SIP domain was incorrect. This may be caused by the IP Access Control List SID already being associated with the Domain.