KF-PDF-XMP: The Factur-X XMP extension is missing
This code shows up when an electronic invoice is validated. Here is what it means, why it fires, and what to change in the file.
Why this code appears
The document metadata does not carry the Factur-X extension, which announces the document type, the attached file name, the version and the profile. Many portals use it to recognise an invoice: without it, an otherwise perfect document is treated as an ordinary PDF.
How to fix it
Add the fx: block to the XMP with DocumentType (INVOICE), DocumentFileName (factur-x.xml), Version and ConformanceLevel.
Where it happens
This check is ours, not a code from the standard: we do not cover enough of EN 16931 to borrow its numbers, and a misattributed official code would send you to fix the wrong field. It concerns PDF.