---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/12101#article
headline: "12101: Invalid Twilio Markup XML version"
url: https://www.twilio.com/docs/api/errors/12101
inLanguage: en
dateModified: 2026-03-11T18:38:39.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 12101: Invalid Twilio Markup XML version

Log Level: ERROR

## Description

The version attribute of the Response root element is not valid.

### Possible causes

* an invalid value was provided for the "version" attribute of the [Response](/docs/voice/twiml#responding-to-twilio) root element.

### Possible solutions

* refer to the [versions](/docs/voice/twiml#responding-to-twilio) documentation for information on valid version values.