How to write memory stream to PDF File of invoice

I have made a plugin, i want custom invoice pdf for which i overridden Nop.Services.Common.IPdfService method

My method  :

public void PrintOrdersToPdf(Stream stream, IList<Order> orders, int languageId = 0, int vendorId = 0)
        {            
             ...
             ...
             ...
             var templatePath = Path.Combine("Sample.pdf");
             var reader = new PdfReader(templatePath);
             var stamper = new PdfStamper(reader, stream);

        }
Everything works without error, stream gets loaded with lenth,capacity.

But after invoice gets downloaded , it does not open
Error : Failed to open PDF document.

Please suggest what to do.

Does it work if you use File Explorer and go to your Downloads folder and open it from there?  (If so, then it's a probably a browser setting)

No, it's not opening from downloads folder.