---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/21420#article
headline: "21420: ApplicationSid is not accessible"
url: https://www.twilio.com/docs/api/errors/21420
inLanguage: en
dateModified: 2025-12-18T21:40:49.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 21420: ApplicationSid is not accessible

Log Level: ERROR

## Description

You specified a VoiceApplicationSid or SmsApplicationSid for a new phone number that is not controlled by your account, or is invalid. Please specify an ApplicationSid that you've created in your [Account Dashboard](/user/account/apps).