How to show a message and send a file using ASP.NET

Question

I generate a set of letters in a file, but if there are errors then the file may be incomplete. I want to send the file anyway, but with a warning to the user. So I have this:

Answer 1

I would suggest to have a page which would instruct the users the file download will begin shortly and in this page, you can display any warnings.

This page would make a separate request for the file, using JS / meta refresh and continue the download. You may also want to provide a direct link, if the download doesn't begin in specified time.

Answer 2

You can't return HTML and another response (for file's stream) in single GET.

You can return HTML and have link to download file there.