# CUSTOMER_DUPLICATED_IN_FILE

Customer with a NIF/CIF duplicated in the file

<Callout type="info">
**Category:** [Customers](/errors/category/cliente)
</Callout>

| | |
|---|---|
| Retry | After fixing the cause |

## When it happens

A row of the file has the same NIF as an earlier row of the same file. It is reported in the row's errors.

## How to fix it

Keep one row per customer in the file and import it again.

## Retry

Not as is: the same request fails the same way. Fix the cause described above, then send the request again, under a new `Idempotency-Key` if the body changed.

## Returned by

The operations where this code is most likely. The list is not exhaustive.

- [`POST /v1/companies/{company_id}/customers/imports`](/customers/createCompanyCustomerImport)
- [`POST /v1/companies/{company_id}/customers/imports/preview`](/customers/previewCompanyCustomerImport)

## Example response

When this error occurs, the API returns a JSON response with the following shape:

```json
{
  "type": "https://docs.beel.es/errors/CUSTOMER_DUPLICATED_IN_FILE",
  "title": "CUSTOMER_DUPLICATED_IN_FILE",
  "detail": "Customer with a NIF/CIF duplicated in the file",
  "instance": "/v1/<resource>",
  "errors": [],
  "success": false,
  "error": {
    "code": "CUSTOMER_DUPLICATED_IN_FILE",
    "message": "Customer with a NIF/CIF duplicated in the file",
    "details": {}
  },
  "meta": {
    "timestamp": "2026-05-21T10:00:00Z",
    "request_id": "4bf92f3577b34da6a3ce929d0e0e4736"
  }
}
```

The `type` URI is stable and always resolves to this page.

## Message

<Tabs items={["English", "Spanish", "Catalan"]}>
  <Tab value="English">{"Customer with a NIF/CIF duplicated in the file"}</Tab>
  <Tab value="Spanish">{"Cliente con NIF/CIF duplicado en el archivo"}</Tab>
  <Tab value="Catalan">{"Client amb NIF/CIF duplicat al fitxer"}</Tab>
</Tabs>

Send the request with `Accept-Language: <es|en|ca>` to receive the message in your preferred language.

## Other errors in this category

<div className="grid grid-cols-2 gap-3 not-prose">
  <Card title="ALTERNATIVE_ID_AND_NIF_EXCLUSIVE" description="The customer cannot carry both a NIF and an alternative identifier. Use only one" href="/errors/ALTERNATIVE_ID_AND_NIF_EXCLUSIVE" />
  <Card title="ALTERNATIVE_ID_COUNTRY_REQUIRED" description="The country of the alternative identifier is missing (alternative_id.country_code). It is required except for the PASSPORT and NOT_REGISTERED types, which are taken as Spanish when it is omitted." href="/errors/ALTERNATIVE_ID_COUNTRY_REQUIRED" />
  <Card title="ALTERNATIVE_ID_INVALID" description="The alternative identifier is not valid" href="/errors/ALTERNATIVE_ID_INVALID" />
  <Card title="ALTERNATIVE_ID_REQUIRES_SPAIN" description="Type NOT_REGISTERED (07) is only valid for Spain; received country: '‹value›'" href="/errors/ALTERNATIVE_ID_REQUIRES_SPAIN" />
  <Card title="ALTERNATIVE_ID_SPAIN_INVALID_TYPE" description="For customers with country ES only types PASSPORT (03) or NOT_REGISTERED (07) are allowed" href="/errors/ALTERNATIVE_ID_SPAIN_INVALID_TYPE" />
</div>

## Keep exploring

<div className="grid grid-cols-2 gap-3 not-prose">
  <Card title="All Customers errors" description="Every code in this category in one table." href="/errors/category/cliente" />
  <Card title="Error reference home" description="Browse every category or jump to the handling guide." href="/errors" />
</div>

---

Full OpenAPI spec: https://docs.beel.es/api/openapi