Thx Manik,   posted it there and hope someone is able to help. https://community.adobe.com/t5/document-services-apis-discussions/create-pdf-portfolio-via-api-with-signed-and-unsigned-files/m-p/13167984  

Hello Team, hope you can help me. We want to create a PDF collection via the API, to receive in the end a portfolio with signed and unsigned pdfs.   at the moment we use the combinePDF process. the process will be initiated but on polling the status we receive an error "Source PDF is signed and cann...