Issue with Signatures in Adobe Acrobat After Merging a PDF Form Using PyPDF

[pizzapunk22]

Hi everyone,

I'm currently facing a problem when working with a PDF form and PyPDF. I'm using PyPDF to merge PDF files that contain form fields. The merging process itself works fine, and the resulting PDF looks as expected.

However, after merging, I try to use the Sign feature in Adobe Acrobat to add a graphic signature. Unfortunately, it doesn't work – I get the following error message:

The operation failed because Adobe Acrobat encountered an unknown error.

Has anyone encountered this issue before or knows how to fix it? I'd really appreciate any suggestions or workarounds!

from pypdf import PdfWriter

merger = PdfWriter()
merger.append("input.pdf")
merger.write("output.pdf")
merger.close()

I've attached:

The original input PDF
input.pdf

The resulting merged output PDF
output.pdf

Thanks in advance!

[stefan6419846]

Have you tried reviewing the relevant differences in the input and output files? Apart from this, does PdfWriter(clone_from="input.pdf").write("output.pdf") make any difference?

[pizzapunk22]

Thanks for your suggestion! I just tried using PdfWriter(clone_from="input.pdf"), but unfortunately it produces the same result.

I’ve compared the input and output PDFs, but so far I haven’t been able to identify any structural differences that could explain the issue. The form fields appear to be preserved correctly, and visually the files look the same.

Still stuck for now, but I appreciate the help!

[pubpub-zz]

i've been able to sucessfully sign the file ouput.pdf you've provided. could it be an issue with your acrobat installation ?
output-6a.pdf

[pizzapunk22]

Thanks for checking! I just tested it, and you're right — adding a digital electronic signature works for me too.

However, what doesn’t work is using the “Fill & Sign” feature to place a handwritten-style signature or initials anywhere on the page. When I try that, Acrobat throws the "unknown error" message.

Would you mind checking if that specific type of signature works on your end as well?

Thanks again!