errorubl-2.1

UBL-SR-05:ID elements must be unique

ID elements within scope must have unique values.

Severity
Fatal
Rule set
ubl-2.1
Country
All EU
Fix type
CONFIRM
Confidence
90%
Category
structural

Engine Classification

Requires user confirmation before application

What is UBL-SR-05?

UBL-SR-05 is a fatal validation rule defined in the ubl-2.1 specification. It validates the PaymentTerms 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/cac:PaymentTerms

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Why This Error Matters

Invoice will be rejected by EN16931 validators. These structural constraints ensure consistent processing by receiving systems.

UBL-SR-05 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.

Validator Behavior

  • ·Causes invoice rejection
  • ·Fails UBL schema validation
  • ·Error returned: UBL-SR-05
  • ·Specification: ubl-2.1

How to Fix It

1.

Check line IDs

InvoiceLine/ID must be unique

2.

Check other IDs

AllowanceCharge, TaxSubtotal, etc.

XML Example

Generic example based on the rule's target XPath. Your actual XML structure may differ.

Before
<!-- Required block is missing -->
<!-- <cac:PaymentTerms> ... </cac:PaymentTerms> -->
After
<!-- Add the required block -->
<cac:PaymentTerms>
  <!-- child elements -->
</cac:PaymentTerms>

Technical Reference

XPath/Invoice/cac:PaymentTerms
Specubl-2.1
Operationremove_duplicates
StrategyRemove duplicate payment terms, keeping the first occurrence

Common 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

Seeing this in production? The API handles UBL-SR-05 automatically. See the fix response →

Frequently Asked Questions

ID elements within scope must have unique values.

Ensure each ID value is unique within its context. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.

Yes, UBL-SR-05 is a critical error that will cause invoice rejection. It must be fixed before submission.

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Last updated: 21 February 2026

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