Signature invalid after form fill-in

[pTDd6e9QiLEa]

I am following the 'Fill Form Fields in PDF' example. The PDF used as input has been previously signed. When I open the PDF after and click on the signature a message box opens 'Signature is INVALID. - The document has been altered ...' and when I click on 'Signature Properties ...' the message box says that 'The certifier has specified that Form Fill-in ... [is] allowed'. How do I do Form Fill-in without invalidating the signature?

[Simon.yang]

Hello,

Thanks for your post. I am sorry it disobeys the signature rules. Once you have changed the content of a PDF file, the signature will be invalid. I suggest you sign the PDF file after filling the form fields. Please refer to the below documentation to sign a PDF file.
https://www.e-iceblue.com/Tutorials/Spi ... -Code.html

Best regards,
Simon
E-iceblue support team

[pTDd6e9QiLEa]

Thank you for your reply. I want to be sure I understand -- Should the signature be invalidated even if IncrementalUpdate is True? Does Spire.PDF have something like Append mode that would prevent the original PDF from being modified and only append changes at the end? (I think you may have already answered this, but wanted to be sure)

[Simon.yang]

Hello,

Thanks for you reply. I am regret to tell you that there isn't a workaround to meet your requirement except signing after editing the PDF file. Also the IncrementalUpdate will not help in this case.

Best regards,
Simon
E-iceblue support team