Where do I set Response.TrySkipIisCustomErrors?

Question

I working on a custom 404 page and keep getting a 500 error from IIS7. After doing some research I found I need to set "Response.TrySkipIisCustomErrors=true;"

Where do I set that value? Can it be set in anyway with php or within the web.config file?

my 404 web.config code is:

<customErrors mode="On">   
 <error statusCode="404" redirect="404.html"/>
</customErrors>

Answer 1

web server isn't running apachee so the web.config file didn't work. Had to have the server admin configure IIS.