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Add signature to existed signature fields


I’ve create two pdfs, one with Adobe Live Cycle Designer(V11.0.0.20130303.1.892433) - “Screen Capture-3.pdf”, another with Adobe Acrobat Pro DC 2015 - “Screen Capture - 2.pdf”.

If I add signature to existed signature fields in pdf which created in Adobe Acrobat Pro DC 2015, it works correctly.

But if I want to add signature to existed signature fields in pdf which created with Adobe Live Cycle, I get error - "Signature field ‘Signature1[0]’ is not defined."

Could you tell me what is difference?
I use Aspose.pdf version - 11.3.0.


var signatureFields = Document.Form.Fields.Where(item => item is SignatureField).Cast().ToList();

var signature = new PKCS1(signatureStream)
Authority = signatureInfo.Authority,
Reason = signatureInfo.Reason,
Location = signatureInfo.Location,
ContactInfo = signatureInfo.ContactInfo,
ShowProperties = signatureInfo.ShowProperties,
Date = DateTime.Now

signatureFields.ForEach(signatureField => signatureField.Sign(signature, pfxStream, _password));

The same result if i use PdfFileSignature from examples but only for existed signature fields

Hi Vitalii,

Thanks for contacting support.

I have tested the scenario using following code snippet using Aspose.Pdf for .NET 11.3.0 where I have used following code snippet (based on your shared code) and I am able to notice ApplicationException: Signature field ‘Signature1[0]’ is not defined exception when using Screen+Capture-3.pdf. However when using same code snippet over Screen+Capture-2.pdf, I am getting System.ArgumentException: Stream was not writable error. For the sake of correction, I have logged this problem
PDFNEWNET-40276 in our issue tracking system. We will
further look into the details of this problem and will keep you updated on the
status of correction. Please be patient and spare us little time. We are sorry
for this inconvenience.


Document doc = new

Document newdoc = new Document();

for (int i = 0; i <= 3; i++)




newdoc.Convert("c:/pdftest/log.txt", PdfFormat.PDF_A_1B, ConvertErrorAction.Delete);



I’ve investigated this problem and find out that this problem relate with names which Adobe Live Cycle set to signature field.

If I set Field name Signature1[0] in Adoble Live Cycle - process of add signature is not working . Error - Signature field 'Signature1[0] is not defined.'
After converting this pdf from Adobe Reader Pro - error is the same.
But when I change signature field from Signature1[0] to Signature1.
Everything works fine.

Hi Vitalii,

Thanks for sharing the details.

We will surely consider this information while resolving the problem and as soon as we have some definite updates, we will let you know.