Unable to Upload files larger than 28Mb : Error 404

For an unknown reason, I'm unable to upload files larger than 28Mb on a Sharepoint Site, and I got an "Error 404 Page" after 5 to 10 seconds, depending of the file's size.

But the strange thing, is that I'm able to upload the same file (same extension, size) on another Site and located on another Web App.

I tested with multiple upload, without any success for the larger file :

Next step was to check the SharePoint configuration, and specially concerning the erroneous Web App.

-          Maximum Upload Size is correctly set

-          Web Page Security Validation expiration time is also correctly set.

Now, it remains the IIS, ASP to be checked.

To do so, I googled a little bit and after a little cleaning, I was able to point 3 specific Microsoft documents:

-          http://support.microsoft.com/kb/925083

-          http://support.microsoft.com/kb/942074
-          http://support.microsoft.com/kb/925083

The first had the exact problem that I was facing, but their solution gave me error after an IISReset.

And the second document, gave me the correct file to change :

I simply added the "<requestLimits maxAllowedContentLenght="52428800" />" under the 
"<requestFiltering>" node:

  















 The third documents is requesting to add a parameter into the "web.config" files in two places on the server :

     - First path : in the 12-Hive folder, under Template => Layouts

 

     - Second path : in inetpub, in the Web App folder

 

A IISReset later, let's test again :

Et voilà !

The 2 largest files are now on my SharePoint Site:

Nb1: Do not forget to change also on all your WFE servers.
Nb2: The manipulation was completely successfull in our Test Environment, but not in Production...
  ==>> Update : all is working.
  Issue was due because I forgot the add "<requestLimits maxAllowedContentLenght="52428800" />" parameter to the "applicationHost.config" file on the 2 WFE Servers (it was done on the CA Server only in Production)

That's all folks