The solution is to use SetMaxSize with the second argument as False, so that AspUpload will truncate
the file rather than rejecting it with an error. Then your code can iterate through the Upload.Files
collection, check to see if the file size equals the specified maximum (which will indicate that
truncation occurred), and alert the user.
<%
Set Upload = Server.CreateObject("Persits.Upload")
Upload.SetMaxSize 50000, False 'limit to 50 KB, do not throw an error
Upload.Save 'save to memory
For Each file In Upload.Files
If file.Size = 50000 Then
'This means the file was truncated
Response.Write "This file is too large: " & file.FileName
Else
file.SaveAs ...
End If
Next
%>