---
page_type: error
code: 48003
message: "48003: Callback returned an invalid response"
level: ERROR
product: Frontline
---

## Description

Callback returned an invalid response

### Possible Causes

- Your Frontline integration service returned a response which is invalid.
- Your service returned a response that was too large. Responses are capped at 64k.

### Possible Solutions

- Make sure that callback returns a valid JSON which has the required fields that are defined in Frontline Docs.
- Make sure that your response size is less than 64k.