For each PDF/A-1 validation issue we try to explain what it means and, if possible how to resolve it. For a more technical explanation of the issue we quote the related section of the ISO 19005-1 PDF/A Specification.
The document contains PostScript. This could be 3-D content or form fields. Use of PostScript can cause PDF files to print incorrectly and therefore is not allowed in PDF/A.
How can I fix it?
Do not use PostScript when creating your PDF documents.
If you are working with a legacy document, simply open your PDF file in Solid PDF Tools and then File | Save As PDF/A. This will remove prohibited PostScript parameters in your PDF/A file.
6.2.7 - ISO 19005-1 PDF/A Specification:
A conforming file shall not contain any PostScript XObjects.
NOTE: PostScript XObjects contain arbitrary executable PostScript code streams that have the potential to interfere with reliable and predictable rendering.