DE-R-002
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-002
When both seller and buyer are located in Germany, the seller contact group (BG-6) must be provided.
How to fix it
In the seller Party block add cac:Contact with a name, telephone and e-mail.