Wrong namespace in the invoice: xmlns for FA(3)

What this error means

The Faktura element doesn't carry the FA(3) namespace, so the schema doesn't recognise the file as an FA(3) invoice. The xmlns attribute on this element must have exactly the value http://crd.gov.pl/wzor/2025/06/25/13775/.

The namespace identifies the version of the template. The validator uses it to pick the schema it checks the file against. KSeF (Poland's national e-invoicing system) also checks the invoice against the schema, and since 1 February 2026 the invoice template in force is FA(3). Until the address matches, the validator checks nothing else: you get only this one message, on the Faktura element. Once it's fixed, the validator checks the whole file, so new errors may appear.

Where it usually comes from

The address must match character for character. The FA(3) schema declares it as its target namespace (targetNamespace). The Ministry of Finance's FA(3) information brochure (broszura) gives the same address with https://, but as the page where the ministry publishes the schema; in xmlns you use the http:// version.

• The FA(2) namespace, http://crd.gov.pl/wzor/2023/06/29/12648/, from an old template or code written before February 2026.
• No xmlns. The element has only the xmlns:etd and xmlns:xsi declarations and no default namespace. Those two declarations can stay; they do no harm.
• A small difference in the address: https:// instead of http:// (for example an address copied from the brochure), a missing trailing slash, swapped digits in the date.
• A prefix that isn't used. The file declares xmlns:fa="http://crd.gov.pl/wzor/2025/06/25/13775/", but the elements have no prefix (<Faktura> instead of <fa:Faktura>). They then don't belong to that namespace. The schema accepts a prefix used consistently on every element, but the simplest option is to declare a default namespace, with no prefix.

<!-- ❌ FA(2) namespace -->
<Faktura xmlns="http://crd.gov.pl/wzor/2023/06/29/12648/">
<!-- ❌ No default namespace -->
<Faktura xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<!-- ❌ https and no trailing slash -->
<Faktura xmlns="https://crd.gov.pl/wzor/2025/06/25/13775">
<!-- ❌ Prefix declared but not used -->
<Faktura xmlns:fa="http://crd.gov.pl/wzor/2025/06/25/13775/">
<!-- ✅ FA(3) -->
<Faktura xmlns="http://crd.gov.pl/wzor/2025/06/25/13775/">

We show this message only when the root element is called Faktura. A root element with any other name produces a general schema error.

How to fix it

1. Open the file and find the opening <Faktura tag, usually on the first or second line.
2. Add or correct the attribute xmlns="http://crd.gov.pl/wzor/2025/06/25/13775/". Copying it is the safest option.
3. If the file was in FA(2) format, the namespace alone isn't enough: the header and the fields in Podmiot2 change too. The full list is in our FA(2) vs FA(3) comparison.

If your software generates the invoice, the address is usually hard-coded in the export template. Fix it there rather than in every file. Then check the invoice again.