Today I stumbled across an interesting issue that came to light only after moving a product to a production server which uses SSL (HTTPS). We had a page that exported some data as an Excel CSV file, by setting the Content-Disposition. Works great on the dev server, but on the live server, Internet Explorer was returning "File not found", with a seemingly random (incorrect) filename. At it refused to download the file.

After quite a bit of digging, and determining that it was a bug with IE... I stumbled across this page which outlined the fix.

http://www.highdots.com/forums/asp-net/content-disposition-doesnt-set-filename-674439.html

Here is the working code in VB.NET:

Context.Response.Clear() 
Response.ClearContent() 
Response.ClearHeaders() 
Response.Cookies.Clear() 
Response.Cache.SetCacheability(HttpCacheability.Private) 
Response.CacheControl = "private" 
Response.Charset = System.Text.UTF8Encoding.UTF8.WebName 
Response.ContentEncoding = System.Text.UTF8Encoding.UTF8 
Response.AppendHeader("Content-Length", f.Length.ToString()) 
Response.AppendHeader("Pragma", "cache") 
Response.AppendHeader("Expires", "60") 
Response.ContentType = "application/vnd.ms-excel" 
Response.AddHeader("Content-Disposition", "attachment;filename=" & fname) 
Response.Write(filecontents) Response.End() 

Dusty Davidson
Lead Software Developer