IIS8.5 > Sites > mysite > Error Pages > 404
Select "Insert content from static file into the error response".
Uncheck "Try to return the error file in the client language".
Enter path to "notfound.html", I've verifieed it is there.
When I visit a page I know isn't there I get:
The page cannot be displayed because an internal server error has occurred.
Why aren't I getting my custom 404 file?
I don't think it's a permission thing, I've tried moving "notfound.html" to several places, one of which is the actual site wwwroot folder which serves the rest of the site.