This code streams large files to our users:
// Open the file.
iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Ope
That exception means that the client downloading the file broke the connection before the file had finished downloading. i.e. The client navigated to another page, or just closed the browser.
I might try moving the if (Response.IsClientConnected) line after your iStream.Read. Even if you did that, I think there still might be a chance to receive this error if the connection is broken while the OutputStream.Write method is still working.