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PDF/A-2a conformance error: The key Marked is required but missing

I am using Aspose.Pdf for .Net v11.1.0 (newest version) to generate PDF/A-2 conformant PDF documents. This works fine for PDF/A-2b, but I get one conformance error when I select PDF/A-2a as output format: The key Marked is required but missing.

Code in attached test program is identical to your sample on this page.
I used this online validator: http://www.pdf-tools.com/pdf/validate-pdfa-online.aspx
When I compare the output file to a file that is indicated to be fully conformant, the difference seems very minor.
Conformant file:
<</MarkInfo<</Marked true>>
File created with Aspose.Pdf for .Net:
<</Lang(nl-NL)/MarkInfo true
As the difference is so very minor, I wonder if there is a workaround? We are required to produce fully conformant PDF files and PDF/A-2a is preferred over PDF/A-2b.

Hi Berend,


Thanks for your inquiry. I have converted your input.pdf file to PDFA2a using Aspose.Pdf for .NET 11.1.0 and tested the compliance with both Adobe Acrobat XI Preflight tool and online PDF-Tools but unable to notice any problem. Please find attached screenshot for your reference.

Please note we follow Adobe Preflight for validating PDF/A conformance. As.all tools on the market have their own “representation” of PDF/A conformance. Please check this article on PDF/A validation tools for reference. We chose Adobe products for verifying how Aspose.Pdf produces PDF files because Adobe is at the center of everything connected to PDF.

Please feel free to contact us for any further assistance.

Best Regards,

Hi Berend,


Thanks for contacting support.

Adding more to Tilal’s comments, I have also tested the scenario on Windows 8.1 while using VisualStudio 2015 where I have used Aspose.Pdf for .NET 11.1.0 and as per my observations, Adobe Acrobat is properly validating PDF/A compliance. Please note that Aspose.Pdf for .NET is developed according to PDF specifications from Adobe and PDF/A compliance is developed accordingly. Furthermore, please note that every third component / application has their own PDF/A specifications, so it would be quite difficult to comply with their standards. For your reference, I have also attached the output generated over my end.