---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/48001#article
headline: "48001: Callback URL is not set"
url: https://www.twilio.com/docs/api/errors/48001
inLanguage: en
dateModified: 2026-06-09T11:00:42.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 48001: Callback URL is not set

Log Type: APPLICATION

Log Level: WARNING

## Description

You tried to use a Frontline feature that requires a Callback URL, but no Callback URL is configured for your Frontline setup. Configure the Callback URL in Frontline before retrying the request.

### Possible causes

* No Callback URL is configured in Frontline.
* The Frontline configuration is incomplete for the feature you are trying to use.
* Your application is calling a Frontline workflow or action that depends on a configured Callback URL.

### Possible solutions

* Open the Frontline configuration for your account and add a valid Callback URL.
* Verify that the Callback URL points to an endpoint your application serves and can receive requests on.
* Confirm that the URL is correctly formatted and uses a publicly reachable `https` endpoint if your integration requires it.
* Retry the request after you save the updated Frontline configuration.

#### Additional resources

* [Frontline documentation](/docs/frontline)
* [Twilio IAM documentation](/docs/iam)