NullReference when removing a signature from a PDF Document

Aspose.PDF Product Family
1

Hello all,


When I try to remove a signature from certain pdf documents I’ get a nullreference exception without any further details. The code is

using AspKit = Aspose.Pdf.Facades;

using (AspKit.PdfFileSignature pdfSig = new AspKit.PdfFileSignature())
{
pdfSig.BindPdf(PdfPath);
int anzahlSignaturen = pdfSig.GetSignNames().Count;
foreach (string signName in pdfSig.GetSignNames())
{
pdfSig.RemoveSignature(signName, true);
}
pdfSig.Save(PdfPath);
}

It works with most documents but with some pdf documents it does not work. May be its because they are PDF/A documents.

I am using Apsose.Pdf Kit Version 8.5

I enclosed the PDF document that results to an error.

Thank you for taking your time looking into this,
Kind regards,
Peter

2

Hi Peter,

Thanks for contacting support.

It appears that you are using legacy Aspose.Pdf.Kit for .NET for signature removal. However during my testing with latest release of Aspose.Pdf for .NET 11.4.0 where I have used following code snippet and I am unable to notice any issue. Can you please try using the latest release and share your findings.

Please note that starting July-2011, Aspose.Pdf.Kit for .NET was merged into Aspose.Pdf for .NET and all its classes and enumerations were merged under Aspose.Pdf.Facades namespace of Merged Aspose.Pdf API. For more information, please visit

  • [Migration from Aspose.Pdf.Kit](http://www.aspose.com/docs/display/pdfnet/Migration+from+Aspose.Pdf.Kit)
  • [Changes in Operator class names](http://www.aspose.com/docs/display/pdfnet/Changes+in+Operator+class+names)

[C#]

using (Aspose.Pdf.Facades.PdfFileSignature
pdfSig = new Aspose.Pdf.Facades.PdfFileSignature())<o:p></o:p>

{

pdfSig.BindPdf("c:/pdftest/TestDokumentSigned.pdf");

int anzahlSignaturen = pdfSig.GetSignNames().Count;

foreach (string signName in pdfSig.GetSignNames())

{

pdfSig.RemoveSignature(signName, true);

}

pdfSig.Save("c:/pdftest/TestDokumentSigned_Removed.pdf");

}