BR-01
A rule of the European standard EN 16931 – applies to every invoice following the standard, including Peppol BIS Billing 3.0.
What this error means
BR-01
The invoice has no specification identifier (CustomizationID, BT-24) — receivers cannot tell which rule set the invoice follows.
How to fix it
Add cbc:CustomizationID with the Peppol BIS Billing 3.0 value: urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0.