430: Invoice file failed verification

The usual cause

KSeF requires well-formed XML 1.0, encoded in UTF-8 without a byte order mark, valid against the schema declared when the session was opened, with no processing instructions and none of the discouraged Unicode characters. Check any details in the response and whether the file matches the declared schema.

How to fix it

Correct any file errors, check the file against the declared schema, and send it again.

The code as published

Błąd weryfikacji pliku faktury

Official text in its original language, from Ministerstwo Finansów, KSeF 2.0 Przewodnik dla Integratorów (github.com/CIRFMF/ksef-api), Copyright (c) 2025 Ministerstwo Finansów, under MIT License.

Read the official document . Source: KSeF API 2.0, specyfikacja OpenAPI (open-api.json), version 2.9.0, published by Ministerstwo Finansów, read on 8 November 2026.

Look at your file

Open the file in your browser to see what it holds: Open a Polish KSeF invoice. Open a Polish KSeF invoice

Other KSeF codes

• 410 No permission to issue this invoice
• 415 Invoice with an attachment not accepted
• 440 Duplicate invoice
• 450 Invoice content failed the semantic checks

All KSeF codes

Updated 8 November 2026