itextsharp"Object reference not set to an instance of an object" error

Ensure that PdfReader is correctly initialized. You're passing image to it, which is a byte array, but PdfReader typically expects a file path or a stream.

PdfReader readerInvoice = new PdfReader(image);

This approach might not work as expected because the PdfReader constructor expects a file path, a byte array, or a stream, but it doesn't directly handle the content of a PDF file stored in a byte array.

if (model.Pdfdoc != null)
{
    byte[] image = new byte[model.Pdfdoc.ContentLength];
    model.Pdfdoc.InputStream.Read(image, 0, image.Length);

    System.UInt32 mimetype;
    FindMimeFromData(0, null, image, 256, null, 0, out mimetype, 0);
    System.IntPtr mimeTypePtr = new IntPtr(mimetype);
    model.filetype = Marshal.PtrToStringUni(mimeTypePtr);
    Marshal.FreeCoTaskMem(mimeTypePtr);

    iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(Server.MapPath("~/Images/Watermark.png"));
    img.SetAbsolutePosition(0, 80f);
    img.ScaleAbsolute(600f, 600f);

    using (MemoryStream pdfStream = new MemoryStream(image))
    {
        PdfReader readerInvoice = new PdfReader(pdfStream);
        int n = readerInvoice.NumberOfPages;

        using (MemoryStream ms1 = new MemoryStream())
        {
            using (PdfStamper stamper = new PdfStamper(readerInvoice, ms1, '\0', true))
            {
                for (int page = 1; page <= n; page++)
                {
                    PdfContentByte over = stamper.GetOverContent(page);
                    over.AddImage(img);
                }
                stamper.Close();
            }

            byte[] bytesInStream = ms1.ToArray();
            ms1.Close();

            image = bytesInStream;
        }

        if (model.filetype.Equals("application/pdf"))
        {
            model.Pdf = image;
        }
    }
}

Hello Garima,

You can skip pdf version or you can assign as below,

using (PdfStamper stamper = new PdfStamper(readerInvoice, ms1, readerInvoice.PdfVersion, true))
{
    for (int page = 1; page <= n; page++)
    {
        PdfContentByte over = stamper.GetOverContent(page);
        over.AddImage(img);
    }
    stamper.Close();
}

If you wish to skip version then use below,

using (PdfStamper stamper = new PdfStamper(readerInvoice, ms1))
{
    for (int page = 1; page <= n; page++)
    {
        PdfContentByte over = stamper.GetOverContent(page);
        over.AddImage(img);
    }
    stamper.Close();
}

Jayraj Chhaya Sir,

here is the screeshot where i am getting error

Hi Garima Bansal,

Please share screen shot or error message so I can help you and give some suggestion accrodingly.

Jayraj Chhaya Sir,

i checked the readerInvoice object is not null, somehow code works but still getting the error.

The "Object reference not set to an instance of an object" error typically occurs when you are trying to access a member or property of an object that is null. In the provided code snippet, the error is occurring on the line using (PdfStamper stamper = new PdfStamper(readerInvoice, ms1, '\0', true)).

To troubleshoot this issue, you should check if the readerInvoice object is null before using it to create a new PdfStamper instance. You can add a null check like this:

if (readerInvoice != null)
{
    using (PdfStamper stamper = new PdfStamper(readerInvoice, ms1, '\0', true))
    {
        // Rest of the code
    }
}

By adding this null check, you ensure that the PdfStamper is only created when the readerInvoice object is not null, preventing the "Object reference not set to an instance of an object" error.

Additionally, make sure that you have imported the necessary namespaces for iTextSharp:

using iTextSharp.text;
using iTextSharp.text.pdf;

If the issue persists, please provide more information about the specific error message and any additional code or stack trace that may be relevant.