When we use PdfStamper to merge fields. we will find
"This file is damaged, Adobe acrobat can not repair the document
most adobe versions, give message “This file is damaged”, but it can repair.
Unfortunately some versions can not repair."
MemoryStream stream = new MemoryStream();
PdfReader reader = new PdfReader(path);
PdfStamper stamper = new PdfStamper(reader, stream);
AcroFields af = stamper.AcroFields;
af.SetField("CurrentDate", DateTime.Now.ToShortDateString());
I try to change memoryStream to filestream. no error again.