---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/40157#article
headline: "40157: Dequeue Instruction does not have a valid 'status_callback_url' parameter"
url: https://www.twilio.com/docs/api/errors/40157
inLanguage: en
dateModified: 2026-06-08T11:29:20.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 40157: Dequeue Instruction does not have a valid 'status\_callback\_url' parameter

Log Type: APPLICATION

Log Level: ERROR

## Description

This error occurs when your Assignment Callback response includes a `dequeue` instruction with a `status_callback_url` value that TaskRouter cannot use. In a `dequeue` instruction, `status_callback_url` is optional, but if you provide it, it must be a well-formed `http://` or `https://` URL string that TaskRouter can use for asynchronous webhook `GET` requests about the worker call.

### Possible causes

* You provided `status_callback_url` as an empty string.
* You provided `status_callback_url` with the wrong data type instead of a URL string.
* The `status_callback_url` value is not a well-formed `http://` or `https://` URL.
* Your application generated a `dequeue` instruction payload where `status_callback_url` was serialized incorrectly, so TaskRouter did not receive a valid URL string.

### Possible solutions

* Set `status_callback_url` to a complete `http://` or `https://` URL string.
* Remove `status_callback_url` from the `dequeue` instruction if you do not need asynchronous worker call status webhooks.
* Verify that your Assignment Callback returns valid JSON for the `dequeue` instruction and that `status_callback_url` is serialized as a string.
* If you also send `status_callback_events`, provide a valid `status_callback_url` so TaskRouter has a destination for those event webhooks.

#### Additional resources

* [Handling Assignment Callbacks](/docs/taskrouter/handle-assignment-callbacks)
* [Queueing Twilio calls with TaskRouter](/docs/taskrouter/twiml-queue-calls)
* [Webhooks (HTTP callbacks): Connection Overrides](/docs/usage/webhooks/webhooks-connection-overrides)