> ## Documentation Index
> Fetch the complete documentation index at: https://moengage-doc-2298-s2s-type-case-sensitive.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Why Do SMS or Connector Campaigns Display Bad Request Errors?

> Fix bad request errors in SMS or connector campaigns caused by invalid, empty, or improperly formatted mobile numbers in your MoEngage user data.

## Problem

Within the campaign **Error breakdown**, a significant number of users encounter the following message:

Bad Request

<img alt="image (1).png" src="https://mintcdn.com/moengage-doc-2298-s2s-type-case-sensitive/RrlLMYNS4H9ufWIz/images/moengage_3cfb49.png?fit=max&auto=format&n=RrlLMYNS4H9ufWIz&q=85&s=1b7a73ab1e33e401dba20b2d67a8f42a" width="760" height="270" data-path="images/moengage_3cfb49.png" />

## Explanation

* If you encounter this error, the payload sent to third-party vendors is incorrect.
* The mobile number field is empty, none, N/A, undefined, null, or 0.
* The mobile number contains a Unicode character.
* The length of the mobile number must be less than four, or it cannot be converted to the E.164 format.

## Solution

To resolve this error, ensure that the phone number is updated to a valid format.

For more information, refer to [Configure Custom Connector (Service Provider).](/user-guide/campaigns-and-channels/sms-mms-and-rcs/sms/getting-started-with-sms/configure-custom-connector-for-sms)