CRP20115

El valor del campo Cantidad debe ser "1".

In English The Concepto of a payment receipt has Cantidad 1.

error: the document is invalid

What the rule checks

As the rule set's publisher wrote it. The rule runs on every element the context matches, and fails where the test is false; the validator reports the line of that element.

Context
/cfdi:Comprobante[@TipoDeComprobante = 'P']/cfdi:Conceptos/cfdi:Concepto
Test
mx:dec(@Cantidad) = 1

Checked with CFDI 4.0