---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/16011#article
headline: "16011: Conference Event: Error Response to Callback URL"
url: https://www.twilio.com/docs/api/errors/16011
inLanguage: en
dateModified: 2026-07-08T18:16:12.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 16011: Conference Event: Error Response to Callback URL

Log Level: WARNING

## Description

Twilio returns This error when it receives an error response while sending a conference event to the callback URL configured on the conference. Conference events are sent to the `statusCallback` URL, and the events that trigger those requests are controlled by `statusCallbackEvent`. Twilio expects status callback webhooks to return a simple `200 OK` response.

### Possible causes

* The `statusCallback` URL configured for the conference is incorrect, or the first participant set a different URL than the one you intended, because later participants cannot override it.
* Your webhook endpoint returned a non-`200 OK` response, such as a `4xx` or `5xx`, when Twilio sent the conference event callback.
* Your webhook handler does not accept the request method Twilio is using. For conference status callbacks, `statusCallbackMethod` defaults to `POST`.

### Possible solutions

* Verify the `statusCallback` URL for the conference and make sure the first participant to join supplies the correct value, since later `statusCallback` values are ignored.
* Update your webhook handler so it successfully receives the conference event request and returns `200 OK`.
* Confirm the endpoint accepts the configured request method, and use `POST` unless you explicitly configured a different `statusCallbackMethod`.

#### Additional resources

* [TwiML Voice: `<Conference>`](/docs/voice/twiml/conference)
* [Voice Conference](/docs/voice/conference)
* [Webhooks FAQ](/docs/usage/webhooks/webhooks-faq)