DE-R-001
A Peppol Germany national rule (DE-R-*) – applies when the invoice is sent over the Peppol network to a receiver in Germany.
What this error means
DE-R-001
When both seller and buyer are located in Germany, the invoice must contain payment instructions (BG-16).
How to fix it
Add a cac:PaymentMeans block with the payment means (e.g. code 58 and an IBAN).