UBL-CR-001:Disallowed element: ext:UBLExtensions
UBL 2.1 Invoice schema does not include `ext:UBLExtensions`. This element must be removed for EN 16931 compliance.
Engine Classification
Remove disallowed UBL element per EN16931 specification
Confidence: 95% · Applied automatically in pipeline
What is UBL-CR-001?
UBL-CR-001 is a fatal validation rule defined in the UBL 2.1 specification. It validates the ext:UBLExtensions element in the UBL invoice XML.
When this rule fires, the invoice is non-compliant and will be rejected by Peppol access points and national validation services. The sending system receives a rejection response and the invoice does not reach the buyer.
Target path: /Invoice/ext:UBLExtensions
Why This Error Matters
Invoice will be rejected by PEPPOL/EN16931 validators. Safe to remove - this element is explicitly prohibited and contains no required business data.
UBL-CR-001 is a hard failure. Invoices that trigger this rule are rejected at the access point and never reach the recipient. In Peppol networks, this means your sending system receives an MLR (Message Level Response) with a rejection status. The invoice must be corrected and re-sent, adding delay to your payment cycle.
Invoice Navigator can automatically correct this error in your pipeline. The fix is applied with full audit evidence, so your compliance trail remains intact.
Validator Behavior
- ·Causes invoice rejection
- ·Fails UBL schema validation
- ·Error returned: UBL-CR-001
- ·Specification: UBL 2.1
How to Fix It
Check for unclosed tags
Every opening tag must have a matching closing tag
Validate special characters
Use & for &, < for <, > for >
Check encoding
Ensure UTF-8 encoding is declared and used consistently
Use XML validator
Run through an XML syntax validator to find exact error location
Before / After
<Invoice> <ext:UBLExtensions>value</ext:UBLExtensions> </Invoice>
<Invoice> <!-- ext:UBLExtensions removed for EN 16931 compliance --> </Invoice>
Technical Reference
/Invoice/ext:UBLExtensionsCode Example
<?xml version="1.0" encoding="UTF-8"?>\n<Invoice xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2"\n xmlns:cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2"\n xmlns:cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2">\n <!-- Properly structured content -->\n</Invoice>Common Causes
- ·Source ERP exports full UBL 2.1 instead of EN16931 subset
- ·Generic UBL template includes optional elements not needed for e-invoicing
- ·Conversion from another format added unsupported elements
- ·Manual XML editing introduced non-standard elements
- ·Invoice software not configured for EN16931 compliance
Seeing this in production? The API handles UBL-CR-001 automatically. See the fix response →
Commonly Seen In
Frequently Asked Questions
The invoice XML is not well-formed. This means the XML structure has errors like unclosed tags or invalid characters.
Fix the XML syntax errors indicated by the parser. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.
Yes, UBL-CR-001 is a critical error that will cause invoice rejection. It must be fixed before submission to ensure your invoice is accepted by the recipient's system.
Many instances of UBL-CR-001 can be automatically corrected using Invoice Navigator's Fixer tool. Upload your invoice and the tool will identify and fix common issues, including invalid xml syntax.
UBL-CR-001 is commonly seen in exports from Any XML export - manual or automated. These software packages sometimes generate invoices that need adjustment to meet full compliance standards.
See Also
Last updated: 27 February 2026
Handle UBL-CR-001 Automatically in Your Pipeline
The compliance engine auto-remediates this error with controlled safety policies and evidence pack generation.