Does the site have a meaningful and helpful 404 error page that works from any depth in the site?
You’ve requested a page – either by typing a URL directly into the address bar or clicking on an out-of-date link and you’ve found yourself in the middle of cyberspace nowhere. A user-friendly website will give you a helping hand while many others will simply do nothing, relying on the browser’s built-in ability to explain what the problem is.