When uploading large file to an ASP page on an IIS 6.0 server, temp files are created but never saved or IIS returns a 403 error response.
For IIS6.0 users, the AspMaxRequestEntityAllowed property specifies the maximum number of bytes allowed in the entity body of an ASP request. If a Content-Length header is present and specifies an amount of data greater than the value of AspMaxRequestEntityAllowed, IIS may return a 403 error response.
In order to solve this problem and increase the AspMaxRequestEntityAllowed value, open Metabase.XML which is located in c:\Windows\System32\Inetsrv. The simplest way to edit it is with Notepad. Find the line "AspMaxRequestEntityAllowed" and change it to a sufficiently large value to account for your transfers. For example, 20971520 (20MB) would be high enough.
Note: To edit Metabase.XML, you must stop IIS Admin Service from Control Pannel->Administrative Tools->Services, otherwise you can't save Metabase.XML.
Finally, we strongly recommanded that you use the MtaEdt tool to edit this parameter directly!