warningEN16931
UBL-CR-666:This UBL element should not be present in an EN16931 invoice. It is allowed in full UBL 2.1 but not in the EN16931 subse
This UBL element should not be present in an EN16931 invoice. It is allowed in full UBL 2.1 but not in the EN16931 subset.
We can fix this automatically
AUTO-FIX1. Identify the non-EN16931 element. 2. Remove from invoice or move data to EN16931-compliant location.
No manual changes needed
Upload and Fix NowWhy This Error Matters
Invoice will be rejected by EN16931 validators. These conformance rules prohibit UBL attributes and element combinations not in the EN16931 e-invoicing profile. Remove the disallowed attribute or restructure the element.
Common Causes
- AdditionalDocumentReference has both object ID and attachment
- Cannot combine invoice object identifier with embedded doc
- Reference must be either object ID or attachment not both
- Document reference structure invalid combination
- ERP exports conflicting reference types together
Frequently Asked Questions
This UBL element should not be present in an EN16931 invoice. It is allowed in full UBL 2.1 but not in the EN16931 subset.
This UBL element should not be present in an EN16931 invoice. It is allowed in full UBL 2.1 but not in the EN16931 subset. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.
UBL-CR-666 is a warning that may not always cause rejection, but it indicates a potential compliance issue that should be addressed.
Many instances of UBL-CR-666 can be automatically corrected using Invoice Navigator's Fixer tool. Upload your invoice and the tool will identify and fix common issues.
See Also
Last updated: 16 January 2026
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