errorubl-2.1
UBL-SR-02:CAC/CBC namespace declarations required
UBL requires Common Aggregate and Basic Component namespaces.
We can fix this automatically
AUTO-FIXAuto-fix: Keep the first occurrence and remove duplicate elements. EN16931 requires exactly one of this element.
No manual changes needed
Upload and Fix NowWhy This Error Matters
Invoice will be rejected by EN16931 validators. These structural constraints ensure consistent processing by receiving systems.
How to Fix It
1
Add cac namespace
xmlns:cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2"
2
Add cbc namespace
xmlns:cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2"
Technical Details
XPath: /Invoice/@xmlns:cac and @xmlns:cbcCommon Causes
- ERP system exports multiple references where only one is allowed in EN16931
- Data consolidation merged records that should have been deduplicated
- Template or mapping incorrectly configured to output duplicate elements
- Manual editing introduced extra elements
- Invoice conversion from another format did not merge duplicate entries
Frequently Asked Questions
UBL requires Common Aggregate and Basic Component namespaces.
Add cac and cbc namespace declarations. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.
Yes, UBL-SR-02 is a critical error that will cause invoice rejection. It must be fixed before submission.
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Last updated: 16 January 2026
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