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I'm trying to download PDF file using C# and asp.net

using the following code I'm trying to download pdf file from server path but after clicking on download button file not download but the code gets file name and file path.
I think I'm missing something in code so, please help me out
Thank you in advance..
code is :
protected void btn_Download_Template_Click(object sender, EventArgs e)
{
string mainPath = "";
string fileName = "Self_Declaration.pdf";
mainPath = Server.MapPath("~/Template/Self_Declaration.pdf");
FileInfo file = new FileInfo(mainPath);
if (file.Exists)
{
Response.Clear();
Response.ClearHeaders();
Response.ClearContent();
Response.AddHeader("content-disposition", "attachment; filename= ~/Template/Self_Declaration.pdf");
Response.AddHeader("Content-Type", "application/pdf");
Response.ContentType = "application/pdf";
Response.WriteFile(file.FullName);
Response.End();
}
else
{
Response.Write("This file does not exist.");
}
}```

Well I don't have enough reputation points to put this in the comment section, but I think your question has already been answered here

Download PDF file from a Directory Listing

I have used a Gridview Control to display the contents of a directory in asp.net webforms.
The contents are filtered to display only PDF files.
I also have a Button inside a TemplateField. On the click of the button the user should be able to download and save the PDF file.
The columns displayed in the Gridview are File Name, Modified Date and Size.
How can I program the Button click to download and save the PDF file?

I have a function that performs a file download.
public static void DownloadFile(string FilePath, System.Web.HttpResponse response)
{
System.IO.FileInfo file = new System.IO.FileInfo(FilePath);
if ((file.Exists))
{
response.Clear();
response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
response.AddHeader("Content-Length", file.Length.ToString());
response.ContentType = "application/octet-stream";
response.WriteFile(file.FullName);
response.End();
response.Close();
file = null;
}
}
The FilePath parameter is the physical path, so if you have the virtual path (e.g. ~/Folder/file.pdf) might need to use the Server.MapPath(...) function to call the function.

In your Button click event, write the following code.
protected void Button1_Click(object sender, EventArgs e)
{
Response.ContentType = "Application/pdf";
Response.AppendHeader("Content-Disposition", "attachment; filename=Your_Pdf_File.pdf");
Response.TransmitFile(Server.MapPath("~/Files/Your_Pdf_File.pdf"));
Response.End();
}

Download files based on their type, or how to give two options to Response.AppendHeader

I am allowing users to download either a PDF file or a zip file, and when they try to download the file, I want the appropriate file to be downloaded according to its type. For example: if the uploaded file is PDF, then it should be downloaded as a PDF; if the uploaded file is zip, then it should downloaded as a zip file.
I have written this code and I am able to download the files as PDF using "output.pdf" in the append header, but don't know how to give two options to append header so that it downloads the file according to its type.
protected void gridExpenditures_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName == "Download")
{
Response.Clear();
Response.ContentType = "application/octet-stream";
Response.AppendHeader("content-disposition", "FileName=" + e.CommandArgument + "output.pdf");
Response.TransmitFile(Server.MapPath("~/Match/Files/") + e.CommandArgument);
Response.End();
}
}

You can use a utility like this one to detect the content type of the file in question, then render the header like this:
protected void gridExpenditures_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName == "Download")
{
var filePath = Server.MapPath("~/Match/Files/") + e.CommandArgument;
var contentType = MimeTypes.GetContentType(filePath);
if (string.IsNullOrEmpty(contentType))
{
contentType = "application/octet-stream";
}
Response.Clear();
Response.ContentType = contentType;
Response.AppendHeader("content-disposition", "FileName=" + e.CommandArgument);
Response.TransmitFile(filePath);
Response.End();
}
}

You need to set your content type to the appropriate application, instead of octet-stream.
For example I had this to open PowerPoint:
application/vnd.openxmlformats-officedocument.presentationml.presentation
Look up your file type in this link:
http://en.wikipedia.org/wiki/Internet_media_type
I store the uploaded content type in my database for each file.

Download text as file in ASP.NET

I am trying to download some text output from the screen as a text file. Following is the code. It's working on some pages and not working at all on other pages. Can anyone please suggest what's wrong here?
protected void Button18_Click(object sender, EventArgs e){
Response.Clear();
Response.Buffer = true;
Response.ContentType = "text/plain";
Response.AppendHeader("content-disposition", "attachment;filename=output.txt");
StringBuilder sb = new StringBuilder();
string output = "Output";
sb.Append(output);
sb.Append("\r\n");
Response.Write(sb.ToString());
}

As already mentioned by Joshua, you need to write the text to the output stream (Response). Also, don’t forget to invoke Response.End() after that.
protected void Button18_Click(object sender, EventArgs e)
{
StringBuilder sb = new StringBuilder();
string output = "Output";
sb.Append(output);
sb.Append("\r\n");
string text = sb.ToString();
Response.Clear();
Response.ClearHeaders();
Response.AppendHeader("Content-Length", text.Length.ToString());
Response.ContentType = "text/plain";
Response.AppendHeader("Content-Disposition", "attachment;filename=\"output.txt\"");
Response.Write(text);
Response.End();
}
Edit 1: added more details
Edit 2: I was reading other SO posts where users were recommending to put quotes around the filename:
Response.AppendHeader("content-disposition", "attachment;filename=\"output.txt\"");
Source:
https://stackoverflow.com/a/12001019/558486

If that's your actual code, you never write the text to the response stream, so the browser never receives any data.
At the very least, you should need
Response.Write(sb.ToString());
to write your text data to the response. Also, as an added bonus, if you know the length beforehand you should provide it using the Content-Length header so the browser can show the download progress.
You're also setting Response.Buffer = true; as part of your method but never explicitly flush the response to send it to the browser. Try adding a Response.Flush() after your write statement.

Correct usage of Response.Write() in ASP.NET

I am trying to force a download of an XML file when the user visits a page.
This is the code I am using
public partial class GenerateTemplate : LayoutsPageBase
{
protected void Page_Load(object sender, EventArgs e)
{
//.............
//Going about generating my XML
//.............
Response.ClearContent();
Response.AddHeader("content-disposition", "attachment; filename=template.xml");
Response.Write(xmlDoc.InnerXml);
Response.Flush();
Response.Close();
}
}
I am facing a problem that my download window hangs indefinitely, without ever completing the download/Open of the file.
What am I doing wrong? Am I not disposing any objects or closing any connections here?

I've posted a reply to a similar question. To quote myself:
Just a small addition to the other answers. At the very end of a download I execute:
context.Response.Flush();
context.ApplicationInstance.CompleteRequest();
I learned that otherwise, the download sometimes does not complete successfully.
This Google Groups posting also notes that Response.End throws a ThreadAbortException which you could avoid by using the CompleteRequest method.

Try using Response.End() instead of Flush and Close
That's what I have been using in the past.

Have you tried setting the content type and calling Response.End():
protected void Page_Load(object sender, EventArgs e)
{
//.............
//Going about generating my XML
//.............
Response.Clear();
Response.ContentType = "text/xml";
Response.AddHeader("Content-Disposition", "attachment; filename=template.xml");
Response.Write(xmlDoc.InnerXml);
Response.End();
}

You say you want to have a file download With asp.net web forms you would do this:
context.Response.ContentType = //MIME type
// Set the filename
context.Response.AddHeader("content-disposition", "attachment;filename=" + queryFile);
// Stream the file to the client
context.Response.WriteFile(file);