Classic ASP code to download .CSV file - asp-classic

Question

I have a website written in Classic ASP
One page creates a .CSV file from a SQL database and stores it in the root directory along with a "Click Here" link to download it to the users PC
It has been working fine for many years and is still working fine when downloading small files, but now it comes up with a "THIS PAGE CAN'T BE DISPLAYED" error when downloading a .csv file (in this example) of some 785 records
The code is pretty short as below with the one Private Sub that does the download
<%#Language="VBScript"%>
<%Reponse.Buffer = True%>
<%
On Error Resume Next
Dim strPath
strPath = CStr(Request.QueryString("File"))
'-- do some basic error checking for the QueryString
If strPath = "" Then
Response.Clear
Response.Write("No file specified.")
Response.End
ElseIf InStr(strPath, "..") > 0 Then
Response.Clear
Response.Write("Illegal folder location.")
Response.End
ElseIf Len(strPath) > 1024 Then
Response.Clear
Response.Write("Folder path too long.")
Response.End
Else
Call DownloadFile(strPath)
End If
Private Sub DownloadFile(file)
'--declare variables
Dim strAbsFile
Dim strFileExtension
Dim objFSO
Dim objFile
Dim objStream
'-- set absolute file location
strAbsFile = Server.MapPath(file)
'-- create FSO object to check if file exists and get properties
Set objFSO = Server.CreateObject("Scripting.FileSystemObject")
'-- check to see if the file exists
If objFSO.FileExists(strAbsFile) Then
Set objFile = objFSO.GetFile(strAbsFile)
'-- first clear the response, and then set the appropriate headers
Response.Clear
'-- the filename you give it will be the one that is shown
' to the users by default when they save
Response.AddHeader "Content-Disposition", "attachment; filename=" & objFile.Name
Response.AddHeader "Content-Length", objFile.Size
Response.ContentType = "application/octet-stream"
Set objStream = Server.CreateObject("ADODB.Stream")
objStream.Open
'-- set as binary
objStream.Type = 1
Response.CharSet = "UTF-8"
'-- load into the stream the file
objStream.LoadFromFile(strAbsFile)
'-- send the stream in the response
Response.BinaryWrite(objStream.Read)
objStream.Close
Set objStream = Nothing
Set objFile = Nothing
Else 'objFSO.FileExists(strAbsFile)
Response.Clear
Response.Write("No such file exists.")
End If
Set objFSO = Nothing
End Sub
%>
So something has changed in recent months
Ay advice much appreciated
Thanks in advance

Answer 1

Your IIS version and configuration might be needed to help but I know IIS6 introduced a 4MB limit to BinaryWrite. Try sending your file in chunks instead.
<% Response.Buffer = False %>
...
With Server.CreateObject("ADODB.Stream")
.Open
.Type = 1
.LoadFromFile strPath
' Send 256K chunks...
Const intChunkSize = 262144
Do While Response.IsClientConnected And (.Position < .Size)
Response.BinaryWrite .Read(intChunkSize)
Loop
.Close
End With