Error 131 on Acrobat Reader, when pdf is digitally signed

We are using v17.6 of Aspose.Pdf to create our .pdf files, and these work fine. However, when these get a digital certificate applied to them, our users are no longer able to open the files in Acrobat Reader XI. They just see a dreaded “131” error message as soon as they try to open them.

They can preview these digitally-signed .pdf files (including the digital certificate) in Outlook, they can view them using Google Chrome, but in Reader XI, they just see this error.

We urgently need our users to be able to open these files in Reader.
Do you have any suggestions ?

@SaxoInfra

Thanks for contacting support.

Would you please try your scenario while using latest version of Aspose.PDF for .NET 18.4, as it is always recommended to use latest version because it contains bug fixes and improvements. However, if issue still occurs while using latest version of the API, please share your sample PDF document along with complete sample code snippet. We will test the scenario in our environment and address it accordingly.