INVOICE_NUMBER_INVALID_CHARACTERS

When it happens

At issue time, the generated invoice number contains a character the AEAT does not accept: only printable ASCII is allowed, except ", ', <, > and =. The invoice is not issued and the number is not used.

How to fix it

Issue it with another series, or fix the series code or format while the series has no issued invoices, and retry.

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}/invoices
• POST /v1/companies/{company_id}/invoices/{invoice_id}/issue
• POST /v1/companies/{company_id}/invoices/{invoice_id}/corrective
• POST /v1/companies/{company_id}/invoices/{invoice_id}/convert-to-invoice

Rules that cite this code

• NUM-008 An invoice number fits AEAT's length and character set

Example response

When this error occurs, the API answers 422 Unprocessable Content with a JSON body of this shape:

{
  "type": "https://docs.beel.es/errors/INVOICE_NUMBER_INVALID_CHARACTERS",
  "title": "INVOICE_NUMBER_INVALID_CHARACTERS",
  "detail": "The number ‹value› contains characters the AEAT does not accept (‹value›). The invoice was not issued and the number was not used: issue it with another series or, if this one has no issued invoices yet, fix its code or format",
  "instance": "/v1/<resource>",
  "errors": [],
  "success": false,
  "error": {
    "code": "INVOICE_NUMBER_INVALID_CHARACTERS",
    "message": "The number ‹value› contains characters the AEAT does not accept (‹value›). The invoice was not issued and the number was not used: issue it with another series or, if this one has no issued invoices yet, fix its code or format",
    "details": {}
  },
  "meta": {
    "timestamp": "2026-05-21T10:00:00Z",
    "request_id": "4bf92f3577b34da6a3ce929d0e0e4736"
  }
}

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

Message

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

Placeholders like ‹value› are filled in at runtime with the actual values of your request.

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