# Message ID not found

{% hint style="danger" %}
`Message ID not found; it is expected in a receipt`
{% endhint %}

For Unifi to identify what transaction an inbound receipt is for, it needs to locate the message IDs from the inbound request. These IDs are then cross referenced against the Message ID and External Message ID fields on the transaction to make a match. These values are extracted from the request using the Reference lookup script found on the inbound settings of a Receipt message.

This error signifies that Unifi could not find a value for the message ID from the received request, and indicates that the issue is either with the received request, i.e. no message ID given, wrong format, etc or the reference lookup script for this message is incorrect.


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