How do I fix FORMAT-001?

Re-export the file from your invoicing software as a UBL 2.1 or CII D16B e-invoice. You can also use Invoice Navigator's compliance engine to correct this automatically in your pipeline.

Is FORMAT-001 a critical error?

Yes, FORMAT-001 is a critical error that will cause invoice rejection. It must be fixed before submission.

Can FORMAT-001 be automatically fixed?

Many instances of FORMAT-001 can be automatically corrected using Invoice Navigator's compliance engine. The fix is applied in your pipeline with full audit evidence.

errorinternal

`FORMAT-001`:Unrecognized invoice format

Q: Which accounting software causes FORMAT-001?

FORMAT-001 is commonly seen in exports from Software that exports proprietary XML formats instead of standard e-invoice formats, Older ERP systems without UBL 2.1 or CII D16B export capability. These packages sometimes generate invoices that need adjustment.

Your file was read successfully as XML, but it does not contain a recognized e-invoice structure. Supported formats are UBL 2.1 Invoice, UBL 2.1 CreditNote, and UN/CEFACT Cross-Industry Invoice (CII D16B). The file may have been exported in the wrong format, or it may be a different type of XML document (such as an order or dispatch advice).

Severity

Fatal

Rule set

internal

Country

All EU

Fix type

BLOCKED

Engine Classification

Financial or legal field · Modification blocked by policy

Reason: Cannot be auto-fixed. The file does not contain a recognized e-invoice structure (UBL Invoice, UBL CreditNote, or CII CrossIndustryInvoice). Re-export the document from your invoicing software in a supported format.

What is FORMAT-001?

FORMAT-001 is a fatal validation rule defined in the internal specification. It validates the The XML root element does not match any known e-invoice namespace. Expected one of: urn:oasis:names:specification:ubl:schema:xsd:Invoice-2 (UBL Invoice), urn:oasis:names:specification:ubl:schema:xsd:CreditNote-2 (UBL CreditNote), or urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100 (CII). The validator checks the root element and its namespace to determine the invoice format before applying business rules. 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: The XML root element does not match any known e-invoice namespace. Expected one of: urn:oasis:names:specification:ubl:schema:xsd:Invoice-2 (UBL Invoice), urn:oasis:names:specification:ubl:schema:xsd:CreditNote-2 (UBL CreditNote), or urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100 (CII). The validator checks the root element and its namespace to determine the invoice format before applying business rules.

This error requires manual correction — financial fields are protected by policy.

Why This Error Matters

FORMAT-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.

Validator Behavior

·Causes invoice rejection
·Error returned: FORMAT-001
·Specification: internal

How to Fix It

Check the file type

Open the XML file in a text editor. Look at the very first element after the XML declaration. It should be <Invoice>, <CreditNote>, or <CrossIndustryInvoice> with the correct namespace.

Re-export from your software

Go back to your invoicing or ERP software and export the document specifically as an e-invoice. Look for options like 'UBL 2.1', 'Peppol BIS 3.0', 'XRechnung', 'Factur-X', or 'ZUGFeRD'. Avoid generic XML exports.

Validate again

Upload the re-exported file to verify it is now recognized as a valid e-invoice format.

XML Example

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

Before

<!-- Triggers validation error -->
<The XML root element does not match any known e-invoice namespace. Expected one of: urn:oasis:names:specification:ubl:schema:xsd:Invoice-2 (UBL Invoice), urn:oasis:names:specification:ubl:schema:xsd:CreditNote-2 (UBL CreditNote), or urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100 (CII). The validator checks the root element and its namespace to determine the invoice format before applying business rules.></The XML root element does not match any known e-invoice namespace. Expected one of: urn:oasis:names:specification:ubl:schema:xsd:Invoice-2 (UBL Invoice), urn:oasis:names:specification:ubl:schema:xsd:CreditNote-2 (UBL CreditNote), or urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100 (CII). The validator checks the root element and its namespace to determine the invoice format before applying business rules.>

After

<!-- Corrected -->
<The XML root element does not match any known e-invoice namespace. Expected one of: urn:oasis:names:specification:ubl:schema:xsd:Invoice-2 (UBL Invoice), urn:oasis:names:specification:ubl:schema:xsd:CreditNote-2 (UBL CreditNote), or urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100 (CII). The validator checks the root element and its namespace to determine the invoice format before applying business rules.>VALID_VALUE</The XML root element does not match any known e-invoice namespace. Expected one of: urn:oasis:names:specification:ubl:schema:xsd:Invoice-2 (UBL Invoice), urn:oasis:names:specification:ubl:schema:xsd:CreditNote-2 (UBL CreditNote), or urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100 (CII). The validator checks the root element and its namespace to determine the invoice format before applying business rules.>

Technical Reference

XPath

The XML root element does not match any known e-invoice namespace. Expected one of: urn:oasis:names:specification:ubl:schema:xsd:Invoice-2 (UBL Invoice), urn:oasis:names:specification:ubl:schema:xsd:CreditNote-2 (UBL CreditNote), or urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100 (CII). The validator checks the root element and its namespace to determine the invoice format before applying business rules.

Specinternal

StrategyCannot be auto-fixed — the entire file structure is unrecognized. The invoice must be re-exported from the source system in a supported e-invoice format (UBL 2.1 or CII D16B).

Common Causes

·The file is a different XML document type (e.g., purchase order, dispatch advice, catalogue)
·The invoicing software exported a generic XML format instead of an e-invoice format
·The file was exported as a PDF/A with embedded XML (Factur-X/ZUGFeRD) but only the PDF was uploaded
·A custom or proprietary invoice format was used instead of UBL or CII
·The file is a valid e-invoice but uses an unsupported older version of UBL or CII

Seeing this in production? The API handles FORMAT-001 automatically. See the fix response →

Commonly Seen In

Software that exports proprietary XML formats instead of standard e-invoice formatsOlder ERP systems without UBL 2.1 or CII D16B export capability

Related Errors

FORMAT-002

PDF must be PDF/A format

Last updated: 20 February 2026

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FORMAT-001:Unrecognized invoice format