IRS Reject Code X0000-029
A binary attachment submitted in the PDF format must begin with the file header "%PDF-".
This reject indicates that a file has been attached to the return that is not in the PDF format. It could be an image, a text document, a spreadsheet, etc.
Identify the file that caused the reject and remove it from the return. Recreate it as a PDF document and attach it before resubmitting the return.
We recommend opening the PDF document in your PDF software before re-attaching it to the return to be sure that it can be opened.
Additional Information:
Desktop: Where Can I Attach a PDF to a Return?