EN 16931 (European standard) · Error: the invoice is rejected
BR-CL-24 An attachment has a file type that isn't allowed
What it means
Files attached to the invoice (BT-125) must declare a MIME type from a short allowed list: PDF, PNG, JPEG, CSV, Excel (xlsx) and OpenDocument spreadsheet (ods). This attachment declares another type. Some validator setups, such as the KoSIT one for XRechnung, only report it as a notice.
Common causes
- A Word document, ZIP file or XML file is attached.
- The MIME type is written wrongly, for example 'pdf' or 'application/octet-stream' instead of 'application/pdf'.
- An e-mail signature image or logo in an unusual format is attached automatically.
How to fix it
Convert the attachment to PDF (or another allowed type) and set the matching MIME type, or send the document another way.
Who fixes it: The sender, or its invoicing software if it sets the MIME type wrongly.
Invoice fields involved
BG-24 BT-125
Related rules
This is our own plain-language explanation, not the official rule text. The official definition is in the first source below.
Stuck on this error in your own software? We can help: Integration help →