Validation rules
UBL-SR-01 — UBL rule
The contract reference (BT-12) appears more than once — only one cac:ContractDocumentReference with one cbc:ID is allowed.
- Rule
UBL-SR-01— official EN 16931 / XRechnung rule- Severity
- error
- Detected by
- tier 3 — KoSIT validator (authoritative)
- Reachability
- Only reachable when validating your own XML — normbill-generated documents cannot trigger it
The normbill invoice model has no contract reference; generated XML never contains cac:ContractDocumentReference.
How to fix it
Keep a single ContractDocumentReference element in your XML.
UBL-SR-01 auf Deutsch — was bedeutet der Fehler?
Der KoSIT-Validator lehnt die Rechnung ab, weil die Vertragsreferenz (BT-12) mehrfach vorkommt — es ist nur ein cac:ContractDocumentReference mit einer cbc:ID erlaubt.
So beheben Sie den Fehler
Behalten Sie genau ein ContractDocumentReference-Element im XML.
Related rules
UBL-SR-02— The receiving advice reference (BT-15) appears more than once — only one cac:ReceiptDocumentReference with…UBL-SR-03— The despatch advice reference (BT-16) appears more than once — only one cac:DespatchDocumentReference with…UBL-SR-04— The invoiced-object identifier (BT-18) appears more than once — only one cac:AdditionalDocumentReference…UBL-SR-05— Payment terms (BT-20) appear more than once — across all cac:PaymentTerms elements only a single cbc:Note is…UBL-SR-06— A cac:BillingReference contains more than one cac:InvoiceDocumentReference — each preceding-invoice…UBL-SR-07— A cac:BillingReference is present but the preceding invoice number (BT-25, InvoiceDocumentReference/cbc:ID)…
Official sources
- XRechnung specification (KoSIT / xeinkauf.de)
- KoSIT validator on GitHub and the XRechnung validator configuration
Every 422 from the API lists the rule id, the path in your request JSON, a plain-language message and a suggested fix — see the docs overview for the report format.
Or try it live: drop any XRechnung XML on the free validator — same KoSIT-backed report, no account.