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# API - May 19, 2026

## Changed

### Recipient format validation errors now include regex pattern

When registering a Recipient or validating user data in advance, the `INVALID_FORMAT` error type now includes the regex pattern used.

The message now returns, for example: `Regex validation: ^\\d{8}$`

**`API response - HTTP 400`**

```json API response - HTTP 400 {8-9}
{
    "Id": "1a8bff3c-37a4-4a1a-9219-d00a5fd19865",
    "Message": "One or several required parameters are missing or incorrect. An incorrect resource ID also raises this kind of error.",
    "Type": "param_error",
    "Date": 1779197001,
    "Errors": {
        "IndividualRecipient.Address.PostalCode": "LENGTH_MORE_THAN_MAX",
        "LocalBankTransfer.GBP.AccountNumber": "INVALID_FORMAT. Regex validation: ^\\d{8}$",
        "LocalBankTransfer.GBP.SortCode": "INVALID_FORMAT. Regex validation: ^\\d{6}$"
    }
}
```

This change impacts the following endpoints:

* [POST Validate data for a Recipient](/api-reference/recipients/validate-recipient-data)
* [POST Create a Recipient](/api-reference/recipients/create-recipient)

Returning the regex directly in the error message allows your platform to more efficiently resolve the issue in the user's data.

The regex patterns applicable are available on demand from the [GET View the schema for a Recipient](/api-reference/recipients/view-recipient-schema) endpoint.

> **Check**
>
> **Best practice – Retrieve schema and validate data before creation**
>
> Your platform is strongly recommended to dynamically retrieve the schema and validate the user's data before creating the Recipient.