# VF-2003

Source: https://xmlvalid.com/rules/VF-2003

> El contenido de la huella del registro anterior no cumple con las especificaciones: 64 caracteres hexadecimales en mayúsculas.

- Level: warning
- Rule sets: VERI*FACTU checks of the AEAT Validaciones 1.2.2 (8 April 2026)
- Context: `/*:RegFactuSistemaFacturacion/*:RegistroFactura/*/*:Encadenamiento/*:RegistroAnterior`
- Test: `matches($previous, '^[0-9A-F]*$')`

In English: The previous record's fingerprint is not a SHA-256 written as 64 hexadecimal characters in capitals. The record is accepted with errors to correct.

## Why it fails

- The hash is written in lower case, or in Base64 instead of hexadecimal.

## How to fix it

- Copy the previous record's Huella exactly as it was sent: 64 characters, 0 to 9 and A to F.

Validate a document against these rules: https://xmlvalid.com/validate