I am evaluating the iText7 pdfXFA add-on to flatten a Dynamic XFA PDF form. I've created a simple C# Console application and used the C# code example at as a guide.

static void Main(string[] args)
{
    string importFilePath = "Input.pdf";
    string exportFilePath = "Output.pdf";

    if (File.Exists(exportFilePath))
    {
        File.Delete(exportFilePath);
    }

    XFAFlattenerProperties flattenerProperties = new XFAFlattenerProperties()
        .SetPdfVersion(XFAFlattenerProperties.PDF_1_7)
        .CreateXmpMetaData()
        .SetTagged()
        .SetMetaData(
                new MetaData()
                    .SetAuthor("iText Samples")
                    .SetLanguage("EN")
                    .SetSubject("Showing off our flattening skills")
                    .SetTitle("Flattened XFA"));

    XFAFlattener xfaf = new XFAFlattener()
        .SetFlattenerProperties(flattenerProperties);

    xfaf.Flatten(
        new FileStream(importFilePath, FileMode.Open, FileAccess.Read), 
        new FileStream(exportFilePath, FileMode.Create, FileAccess.Write));
}

However, I'm getting the error "AbstractITextEvent is only for internal usage." when it reaches the Flatten() method. The stack trace looks like this:

at iText.Commons.Actions.AbstractITextEvent..ctor()
at iText.Commons.Actions.AbstractProductITextEvent..ctor(ProductData productData)
at iText.Commons.Actions.AbstractProductProcessITextEvent..ctor(SequenceId sequenceId, ProductData productData, IMetaInfo metaInfo, EventConfirmationType confirmationType)
at iTextSharp.tool.xml.actions.PdfXfaProductEvent..ctor(SequenceId sequenceId, IMetaInfo metaInfo, String eventType)
at iTextSharp.tool.xml.actions.PdfXfaProductEvent.CreateFlattenXfaEvent(SequenceId sequenceId, IMetaInfo metaInfo)
at iTextSharp.tool.xml.xtra.xfa.XFAFlattener.Initialize(Stream pdfOutputStream, String oldProducer)
at iTextSharp.tool.xml.xtra.xfa.XFAFlattener.Flatten(Stream xfaInputStream, Stream pdfOutputStream)
at iText7PdfXfaConsole.Program.Main(String[] args) in E:\DevProjects\iText7PdfXfaConsole\Program.cs:line 37

I am using .NET Framework 4.8 in my Console application as that is what we are currently using in our main application. Any recommendations on what I can do to get this to work?

The online demo at seems to do exactly what we require so I'm hoping we can leverage this library in our application.