> ## Documentation Index
> Fetch the complete documentation index at: https://moengage-user-guide.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Why Are Users Not Merged After Using the User Merge API?

## Problem

Users are not merged even after using the User Merge API.

## Explanation

This issue occurs because you have passed the *MoEngage ID* instead of the *ID*.

Please note that the Merge User API is not functional in workspaces where the Identity Resolution feature is enabled.

## Solution

Perform the following steps:

1. *Update the payload*. Update the following payload with the ID that must be merged and retained.
   <CodeGroup>
     ```json Code theme={null}
     {
     “merge\_data”: [
     {
     “merged\_user”: “user\_id\_that\_you\_want\_to\_merge“,
     “retained\_user”: “user\_id\_that\_you\_want\_to\_retain”
     }
     ]
     }
     ```
   </CodeGroup>

2. *Use the correct identifier.* The UID is the unique identifier for a user, which MoEngage stores in the [ID attribute of the user profile](/user-guide/data/user-data/user-profile). Ensure that only the UID/ID attribute in the user profile is used to merge users.

<img src="https://mintcdn.com/moengage-user-guide/_GuRgbivz3px0yNk/images/moengage_896d2c.png?fit=max&auto=format&n=_GuRgbivz3px0yNk&q=85&s=2ffdcd77b83cf088d9bd1b6dc4a61aa8" alt="user profile id.png" width="3020" height="1666" data-path="images/moengage_896d2c.png" />

<Info>
  Only registered users in MoEngage can be merged with another registered user, regardless of the source of creation.
</Info>