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Concatenate vs. ConcatenateForms

Our users concatenate PDFs all day long. I don’t know if some of them have forms or not. Some do, some don’t. Is there a reason why I can’t just use ConcatenateForms() all the time, even if no forms are involved? Because I find that Concatenate() leads to Invalid Cast exception errors a lot, but ConcatenateForms() does not.


Hi David,

I have contacted our development team for the details regarding your scenario. You’ll be updated as some response is received.

We’re sorry for the inconvenience. If you have any further questions, please do let us know.

Hi David,

If you want to concatenate the PDF forms, you can use ConcatenateForms method, and in order to concatenate other PDF files you can use Concatenate method. However, if you use Concatenate method and the input file(s) contain PDF forms, it’ll automatically call the ConcatenateForms method. So, you can always use Concatenate method - in both of these cases.

If you’re having some issue while concatenating simple PDF files or the files with PDF forms then please share the problematic PDF files along with the issue details and we’ll test it at our end.

We’re sorry for the inconvenience and looking forward to help you out.