iTextSharp-generated PDFs now cause Save dialog in Adobe Reader X

I have been using iTextSharp to generate PDF documents for over a year. Unfortunately, with the release of Adobe Reader X, my PDFs now cause a "Do you want to Save?" dialog to appear when closing the PDF document. This does not happen with PDFs that are not generated with iTextSharp. It's really annoying for my users who are opening and closing PDF documents all day long. Are there any properties in iTextSharp that I can set to prevent this from happening?

If it helps, I am using a PdfReader to read data from an existing PDF document (this original document does not cause the Save dialog to appear). I then use a PdfWriter to create a new document and AddTemplate to copy a portion of the original document to the new one.

Solution 1:

The problem is this line:

Response.OutputStream.Write(MS.GetBuffer(), 0, MS.GetBuffer().Length)

The GetBuffer method returns the entire internal buffer which is larger that the actual content. The bad PDF has about 10kb of garbage content at the end (bytes of zero), the good PDF has only a few garbage bytes. Use the ToArray() method of the memory stream to get the PDF file and the problem will be fixed. You will also get smaller files.

byte[] pdf = MS.ToArray();
Response.OutputStream.Write(pdf, 0, pdf.Length);

Also set the "Content-Length" with the length of the pdf array.

Solution 2:

Also add

HttpContext.Current.Response.End();

After completion of your PDF file.