How can I return a 404 error from an asp.net handler?

Question

I have created a handler for downloading a file. I want to return a 404 error if the file does not exists or user does not have rights to download that particular file.

Answer 1

I'm not sure we have enough information about what you're trying to do. Are you using a REST API? If you're using WebApi, it'd be pretty simple:

public IHttpActionResult DownloadFile(string fileName)
{
   if (!File.Exists(fileName))
   {
      return NotFound();
   }

   // Do something

   return Ok(yourFile);
}