---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/13231#article
headline: "13231: Dial->Conference: Invalid endConferenceOnExit value"
url: https://www.twilio.com/docs/api/errors/13231
inLanguage: en
dateModified: 2026-06-08T11:29:20.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 13231: Dial->Conference: Invalid endConferenceOnExit value

Log Level: ERROR

## Description

Twilio returns this error when your `<Dial><Conference>` TwiML sets `endConferenceOnExit` to a value other than `true` or `false`. Use this attribute to control whether the conference ends when that participant leaves. If you omit the attribute, the default value is `false`.

### Possible causes

* Your application sends a value such as `True`, `FALSE`, `yes`, `1`, or another non-boolean string for `endConferenceOnExit`.
* Your TwiML template or helper library inserts extra quotes, whitespace, or other invalid characters into the `endConferenceOnExit` attribute. This causes the final `<Conference>` noun to contain a value Twilio cannot parse as `true` or `false`.
* Your application maps user input or configuration values directly into `endConferenceOnExit` without validating them first.

### Possible solutions

* Set `endConferenceOnExit` to `true` or `false` only. For example, use `<Conference endConferenceOnExit="true">` or `<Conference endConferenceOnExit="false">`.
* If you do not need the conference to end when that participant exits, remove the `endConferenceOnExit` attribute and let Twilio use the default value of `false`.
* Validate the generated TwiML before you return it to Twilio. Confirm that the final XML contains a valid `<Conference>` noun and that `endConferenceOnExit` is set to a supported boolean value.
* If your application builds conference participants dynamically, normalize configuration values before rendering TwiML so only `true` or `false` is passed into the attribute.

#### Additional resources

* [TwiML `<Conference>` noun](/docs/voice/twiml/conference)
* [TwiML `<Dial>` verb](/docs/voice/twiml/dial)
* [Conference Participants resource](/docs/voice/api/conference-participant-resource)