"Cannot access a closed Stream" when trying to return PDF from controller using iText

Question

I'm trying to copy pages from an existing PDF to a new one and return it. I'm writing to the new PDF with memory, but it returns an error stating

Cannot access a closed Stream.

Here is my code:

var ms = new MemoryStream();
 
using PdfReader pdfReader = new PdfReader(pdfStream);
using PdfDocument pdfDocument = new PdfDocument(pdfReader);
 
using PdfWriter pdfWriter = new PdfWriter(ms);
using PdfDocument newDocument = new PdfDocument(pdfWriter);
pdfDocument.CopyPagesTo(1, 2, newDocument);
 
return File(ms, "application/pdf");

Answer 1

You have to call iText.IO.Source.OutputStream<T>.SetCloseStream(false) to prevent the Stream instance from disposing by default when disposing the OutputStream.

using PdfWriter pdfWriter = new PdfWriter(ms);
pdfWriter.SetCloseStream(false);

• Charlieface: Also need to rewind the stream to Position = 0
• Sir Rufo: or return File(ms.ToArray(), "application/pdf");