I’m not supporting IE8 and below, and based on a useragent checked all requests made from one of these browsers are referred to a page where I explain the reason and display links to supported browsers.
Is there an HTTP status code to go along with this? 200 Wouldn’t be right because the user is not getting the page he requested and 505 (Version not supported) refers to an outdated HTTP version, which is also not the case.
I vote for
403 Forbidden “The server understood the request, but is refusing to fulfill it”
but there’s no definitive answer to this.