403.18 - The specified request cannot be executed from current Application Pool
 
 
Hi,

In IIS6 you can separate your several web applications in different application pools. This can come as a great memory management and application isolation improvement to you web environment.

Nevertheless, bear in mind that if you use several application pools and you use IIS Custom Errors pages (for example for the HTTP 404 error), you might start getting the error "HTTP 403.18 - The specified request cannot be executed from current Application Pool". This will happen every time an "application" is not in the same application pool as the "error page of HTTP XXX" generates the HTTP XXX error.

To avoid this problem, you have to create a registry key with the name "IgnoreAppPoolForCustomErrors", type "DWORD" and value 1 under the "HKLM\SYSTEM\CurrentControlSet\Services\W3SVC\Parameters\" folder.

I got this information from the microsoft article http://www.microsoft.com/technet/community/columns/insider/iisi0905.mspx#EJD that seems to have the registry folder incorrect. I found the correct registry folder (the one that worked for me) in the forum article http://blogs.msdn.com/rakkimk/archive/2006/09/01/735684.aspx .

I hope this info is useful for you.

Best Regards,

Daniel