I have an AutoComplete control calling my Controller that has the [Authorize] attribute applied to it. When the session expires the control lets you still type in it and tries to call the controller. Nothing happens on the page to show an issue, but in the browser development tools console, there is a jQuery error reporting a 404 error.
The big question is why is it not either getting a 401 error code or following the redirect it is getting to go to the login page? If it was reporting the correct error code than at least I could capture it and redirect it myself or deal with it as I need to.